Question

explain this!

Answer 1

@dumbcow

Answer 2

@DLS @shamim @dan815 @jhonyy9

Answer 3

guys help please!

Answer 4

@mathslover

Answer 5

@mathslover would you explain?

Answer 6

@ganeshie8

Answer 7

I am not sure for the correct method to solve this quest.

Answer 8

50% Sure though...

Answer 9

at least explain what you know! nobody is helping me! :/

Answer 10

Okay, what is amount here?

Answer 11

100

Answer 12

Wait please...

Answer 13

http://qrc.depaul.edu/StudyGuide2009/Notes/Savings%20Accounts/Compound%20Interest_files/image002.gif

Answer 14

in 6 months time the amount will be 150
then for the other 6 months 150 will become our principal amount which would become 225 in one year
so the 100 will double between 6 months and 1 year

am i right?

Answer 15

thats perfect !

Answer 16

and a very good logic indeed :)

Answer 17

thanks @ganeshie8
i was waiting for someone to help from so long !

Answer 18

np :)

we may use compound interest formula also for this. but that would involve logs

Answer 19

and i don't know that advance maths :P

Answer 20

@mathslover thank you too, at least you tried to help :)

Answer 21

\(100(1+0.5)^t = 200\)

\((1+0.5)^t = 2\)

\(t = 1.7\)

\(t = 1.7 \times 6 \) months

Answer 22

but the practical answer for this wud be "atleast one year" cuz banks wont deposit money to ur account until a full 6 months period completes.

Answer 23

so the answer should be B then?

Answer 24

they update ur balance, oly after every 6 months. so you will see 200+ in ur bank account, oly after 1 year. eventhough, technically you would have earned the same in \(1.7 \times 6\) = 10.2 months.

Answer 25

I would tick B.

Answer 26

you can do this :-

1. if this q is from finance tick B
2. if this q is from math tick A

either case check with your teacher what she wants :)

Answer 27

ok i will take B as the answer then! but in the ques they have asked how long will it take the amount to double, not how long will it take to get the double amount?
so don;t you think it will be A

Answer 28

I was applying logs too.

Answer 29

the problem is it is just a worksheet!

Answer 30

But its complicated ...

Answer 31

yea i see you have a point there :) lets go with A :)

Answer 32

ok then A it is :)

Answer 33

one more thing it might be a dumb question but how did you solve for the power t in the above eq ?

Answer 34

its not dumb q lol :) ive used my calculator

Answer 35

we can solve it without using calculator

Answer 36

no i mean t was the power how did you turn it into a variable?

Answer 37

\((1+0.5)^t = 2 \)

\(1.5^t = 2\)

take log both sides

Answer 38

lets wait for mathslover :)

Answer 39

\(A = P ( 1 + \cfrac{r}{100} ) ^{2 t}\)

\(200 = 100 ( 1+ \cfrac{1}{2} ) ^{2t}\)

\(2 = (\cfrac{9}{4})^t\)

\(2^{2t + 1 } = 9^t\)

\((2t+1) \log 2 = t \log 9 \)

\((2t) \log 2 + \log 2 - t\log 9 = 0 \)

\(t(2\log 2 - \log 9 ) = -\log 2\)

Answer 40

From which I get : \(t = \cfrac{-\log 2}{ 2\log 2 - \log 9}\)

\(t = \cfrac{- \log 2}{ \log (\cfrac{4}{9})}\)

it is sure that t will be positive... (log (4/9) is negative) .. So, I am right yet... :)

Answer 41

\(t = \cfrac{\log 2}{ \log (\cfrac{9}{4}) } \)

\(t = \cfrac{\log 2}{ \log (2.25) }\)

We can say that it approaches to 1... , So t can not be greater than 1 ,..

Answer 42

That is it is option A)

Answer 43

^ This is how I solved it :)

Answer 44

good job, a bit technical for me but i got it!

Answer 45

Though it can be solved in a better manner but my mind was not working at that time and is not working now also :)

Answer 46

Farheen, logs are very interesting. I will suggest you to read some of the basics if you get time.

And thanks :)

Answer 47

nvrmind i now know two methods to solve it


i know log i need to revise the property and if i need any help i will ask you :)

Answer 48

Sure!

Answer 49

Nice deduction mathslover :)

Answer 50

Thanks :)