Let’s do some more

percentage problems. Let’s say that I start

this year in my stock portfolio with $95.00. And I say that my portfolio

grows by, let’s say, 15%. How much do I have now? OK. I think you might be able to

figure this out on your own, but of course we’ll do some

example problems, just in case it’s a little confusing. So I’m starting with $95.00,

and I’ll get rid of the dollar sign. We know we’re working

with dollars. 95 dollars, right? And I’m going to earn, or I’m

going to grow just because I was an excellent stock

investor, that 95 dollars is going to grow by 15%. So to that 95 dollars, I’m

going to add another 15% of 95. So we know we write 15% as a

decimal, as 0.15, so 95 plus 0.15 of 95, so this is

times 95– that dot is just a times sign. It’s not a decimal, it’s a

times, it’s a little higher than a decimal– So 95 plus

0.15 times 95 is what we have now, right? Because we started with 95

dollars, and then we made another 15% times what

we started with. Hopefully that make sense. Another way to say it, the 95

dollars has grown by 15%. So let’s just work this out. This is the same thing as 95

plus– what’s 0.15 times 95? Let’s see. So let me do this, hopefully

I’ll have enough space here. 95 times 0.15– I don’t

want to run out of space. Actually, let me do it up here,

I think I’m about to run out of space– 95 times 0.15. 5 times 5 is 25, 9 times 5 is

45 plus 2 is 47, 1 times 95 is 95, bring down the 5,

12, carry the 1, 15. And how many decimals

do we have? 1, 2. 15.25. Actually, is that right? I think I made a mistake here. See 5 times 5 is 25. 5 times 9 is 45, plus 2 is 47. And we bring the 0 here, it’s

95, 1 times 5, 1 times 9, then we add 5 plus 0 is 5,

7 plus 5 is 12– oh. See? I made a mistake. It’s 14.25, not 15.25. So I’ll ask you an

interesting question? How did I know that

15.25 was a mistake? Well, I did a reality check. I said, well, I know in my head

that 15% of 100 is 15, so if 15% of 100 is 15, how can

15% of 95 be more than 15? I think that might

have made sense. The bottom line is 95

is less than 100. So 15% of 95 had to be less

than 15, so I knew my answer of 15.25 was wrong. And so it turns out that I

actually made an addition error, and the answer is 14.25. So the answer is going to be 95

plus 15% of 95, which is the same thing as 95 plus 14.25,

well, that equals what? 109.25. Notice how easy I made

this for you to read, especially this 2 here. 109.25. So if I start off with $95.00

and my portfolio grows– or the amount of money I have– grows

by 15%, I’ll end up with $109.25. Let’s do another problem. Let’s say I start off with some

amount of money, and after a year, let’s says my portfolio

grows 25%, and after growing 25%, I now have $100. How much did I originally have? Notice I’m not saying that

the $100 is growing by 25%. I’m saying that I start with

some amount of money, it grows by 25%, and I end up with

$100 after it grew by 25%. To solve this one, we

might have to break out a little bit of algebra. So let x equal what

I start with. So just like the last problem,

I start with x and it grows by 25%, so x plus 25% of x is

equal to 100, and we know this 25% of x we can just rewrite as

x plus 0.25 of x is equal to 100, and now actually we have a

level– actually this might be level 3 system, level 3 linear

equation– but the bottom line, we can just add the

coefficients on the x. x is the same thing

as 1x, right? So 1x plus 0.25x, well that’s

just the same thing as 1 plus 0.25, plus x– we’re just doing

the distributive property in reverse– equals 100. And what’s 1 plus 0.25? That’s easy, it’s 1.25. So we say 1.25x

is equal to 100. Not too hard. And after you do a lot of these

problems, you’re going to intuitively say, oh, if some

number grows by 25%, and it becomes 100, that means that

1.25 times that number is equal to 100. And if this doesn’t make sense,

sit and think about it a little bit, maybe rewatch the video,

and hopefully it’ll, over time, start to make a lot

of sense to you. This type of math is

very very useful. I actually work at a hedge

fund, and I’m doing this type of math in my

head day and night. So 1.25 times x is equal

to 100, so x would equal 100 divided by 1.25. I just realized you

probably don’t know what a hedge fund is. I invest in stocks

for a living. Anyway, back to the math. So x is equal to 100

divided by 1.25. So let me make some space

here, just because I used up too much space. Let me get rid of my

little let x statement. Actually I think we know

what x is and we know how we got to there. If you forgot how we got

there, you can I guess rewatch the video. Let’s see. Let me make the pen thin

again, and go back to the orange color, OK. X equals 100 divided by 1.25,

so we say 1.25 goes into 100.00– I’m going to add a

couple of 0’s, I don’t know how many I’m going to need,

probably added too many– if I move this decimal over two to

the right, I need to move this one over two to the right. And I say how many times does

100 go into 100– how many times does 125 go into 100? None. How many times does

it go into 1000? It goes into it eight times. I happen to know that in my

head, but you could do trial and error and think about it. 8 times– if you want to think

about it, 8 times 100 is 800, and then 8 times 25 is

200, so it becomes 1000. You could work out if you like,

but I think I’m running out of time, so I’m going

to do this fast. 8 times 125 is 1000. Remember this thing isn’t here. 1000, so 1000 minus 1000 is 0,

so you can bring down the 0. 125 goes into 0 zero times,

and we just keep getting 0’s. This is just a decimal

division problem. So it turns out that if your

portfolio grew by 25% and you ended up with $100.00

you started with $80.00. And that makes sense, because

25% is roughly 1/4, right? So if I started with $80.00 and

I grow by 1/4, that means I grew by $20, because

25% of 80 is 20. So if I start with 80

and I grow by 20, that gets me to 100. Makes sense. So remember, all you have to

say is, well, some number times 1.25– because I’m growing

it by 25%– is equal to 100. Don’t worry, if you’re still

confused, I’m going to add at least one more presentation

on a couple of more examples like this.

so amazing the instinct we have when we make a mistake.

great teacher

For the second problem, since 1.25 = 5/4, you can divide by 5/4 ( multiply by the inverse, 4/5) which gives you 80 without having to do long division.

noob

Mr. Hernandez had to interview a total of 63

households in his assignment. He has already

finished 28. What percentage of the households

in his assignments has he finished? (Round

your answer to the nearest tenth of a percent.)Help me

just divide 28/63 and it should give 0.44 which is 44%

@vickiormindyb that would cause a run up of inflation.

@demilo1625 looks like 44.44%. just let 28/63=x/100 and cross multiply. 28/63 is the fraction you have, and some number over 100 is the fraction you want.

GENIUS

this didnt help me. can someone help me please? if i get a 2% cash back on $19.40. how much am i getting back?

@vickiormindyb THANK YOU FOR REPLAYING. BUT WHAT IS THE FORMELA FOR THIS PROBLEM? My credit card GIVE ME A 2% CASH BACK ON PURCHEASES I MAKE. I JUST WANT TO SEE IF THERE RIGHT. AND I WANT TO BE ABLE TO DO IT TOO. THANK YOU.

@vickiormindyb OK THANK YOU AGAIN.

@vickiormindyb Hey, thank you very much I was doing it right. I just wasn't sure. Thank you again. Bye

thank you

No offense, but it's 14.25.

Thank you!

My Teacher asked Me to watch this vid >.>

@MrMGD92 because the questions says "it grows" which is addition. for example a crowd of 2 people grows by 5 people is the same as 2+5, so back to the problem once you find the percent you still have to add t to the whole number $95

Does something make a laughing sound at 3:40 ?

Great info thx

you heard of carrying the 1?

Jvgvvvbb

7:10 haha "I just realised you probably dont know what a hedge fund is………I invest in stocks for living"….and probably have several yachts :p Thanks for vid!

Thank you, very helpful video

would've been better if the demo also showed that if x + 0.15x = y, then 1.15x=y, which means you can find out how much something grows by 15% multiplying by 1.15, in one step.

on the excerises with the website I learned that because it comes in handy when its like 50 pounds increased by 125% so £50 (100%) + 125% = 50 * 2.25%

talk faster im not 4 years old

lol

Or instead of doing the percentage and then adding the original number, when GROWING, you can simply add +1 to your percentage, then solve and you'll get the same answer, without having to add the original number again.

13 is what percent of 47?

What's a portfolio?

Great job!

Woahhh, what's up with the quality?! Haha, just kidding.

nice.nice,very nice

100% = 95

15% is x 95×15/100=14.5 this way is easier

thanks, excellent explanations!

g

I always preferred doing 95×1.15

Can you post videos about investment strategies?

Very nice system

I can't belive this video was made when I was 8

that is to cool you work at a hedge fund i studied finance so long and passionately but never got a spot cuz im self educated on it. buy tesla and ripple coin

how is 1.25x the answer to 1x + .25x ?

What is this Video quality

This video is ollld

This is how i do the second one.

If you have $100 after the number has grown with 25%

$100 is 125% of the original number

The original number is 100%.

To find the original number you just have to divide $100 (which is the number you have after it has grown with 25%) with 125 and then you know what 1% is and times that by 100 to find the original number(100%).

I'm bad at explaining so I'll show you my calculations:

100/125= 0.08

0.08*100= 80

Amazing! Thank you so much for your videos. It turns out that maths is not that difficult if someone explains it properly.

What is a port folio?

this was very confusing

lol 11 years ago but he still has the same mic

In the last problem,

Portfolio grows by 25% and the current value is $100

We need to find the initial value x

Which means 125% of x = 100

I.e 1.25*x=100

X= 100/ 1.25

X= 10000/ 125

X= 80

You know it would be a lot easier to just use fractions..

the screen is huge. lol on ur mistake

I think whats a bigger problem is percentages in the thousands. For example:

From 2000, to 25,00 is 1150%. If I divide this by 28 I get approx. 41% a year.

If I take 2000 and do a future value calculator (excel) with 41% a year, I get over 30,000,000. What am I doing wrong? How do I find what percentage growth this is per year.

I do not get it.

7:09 thanks for answering the question

Thank you Mr. Sal!!

Literally just do .15*95 and then add the sun of that and 95 together that's the easiest way, just like he does in the video

this was made 1 month before I was born loooooooool