SOLUTION: Janette Bought a Share of stock on PRT Corporation. The first week, it increased in value 25%. During the second week, it decreased $1.40 in value. The next week it doubled in valu

Algebra ->  Equations -> SOLUTION: Janette Bought a Share of stock on PRT Corporation. The first week, it increased in value 25%. During the second week, it decreased $1.40 in value. The next week it doubled in valu      Log On


   

Question 60259This question is from textbook Pre-Algebra
: Janette Bought a Share of stock on PRT Corporation. The first week, it increased in value 25%. During the second week, it decreased $1.40 in value. The next week it doubled in value, so she sold it. She got $27.20 for it. How much had she paid for it? This question is from textbook Pre-Algebra

Found 2 solutions by smik, uma:
Answer by smik(40) About Me  (Show Source):
You can put this solution on YOUR website!
Pretty good question.


Since we're trying to find the amount she paid we should start off with giving the Initial Investment a variable letter. So, let's say: I = Initial Investment.


Now, we know in the first week 'I' increased in value by 25%. This means that the total value is: I%2BI%2A0.25. If we factor out 'I' we get: I%2A%281%2B0.25%29. So, we can write this as: I+%2A+1.25


In the second week we know that amount decreases by $1.40. Hence, we know can subtract the amount during the first week by this value, giving us a total of: I%2A1.25+-+1.40


In the third and last week the amount doubles, hence we get the following for th total amount: 2%2A%28I%2A1.25+-+1.40%29


Since Janette withdraws $27.20 in the end, we can set this equal to the above and solve:


27.20+=+2%2A%28I%2A1.25-1.40%29 (We can expand this)
27.20+=+2.5%2AI-2.80 (We can add 2.80 to each side)
30.00+=+2.5%2AI (We can divide each side by 2.5 to solve for 'I')
I+=+12


Hence, we know Janette's initial investment was $12.

Answer by uma(370) About Me  (Show Source):
You can put this solution on YOUR website!
Let Janette's cost price be $x
During the first week it increased by 25%
So cost by the end of 1st week = $1.25x
Decrease during the second week = $1.4
So cost by the end of 2nd week = $1.25x - 1.4
Cost at the end of the third week = double the earlier amount
= 2(1.25x - 1.4)
Given that 2(1.25x - 1.4) = 27.2
==> (1.25x - 1.4) = 27.2/2 [dividing by 2 throughout]
==> (1.25x - 1.4) = 13.6
==> 1.25x - 1.4 + 1.4 = 13.6 + 1.4
==> 1.25x = 15
==> 1.25x/1.25 = 15/1.25
==> x = 12
So Janette had paid $12 for the stock.

Good Luck!!!