Problem Solving

Problem 1:
(.8)^-5 / (.4)^-4 =

Problem 2:
Account X interest rate = 6%
Account Y interest rate = 8%
The total invested in these accounts was $50,000 and it increased 7.2%
How much was invested in Account X?

Problem 3:
There are 4 integers. There sum and product is even. What is the max odd numbers you can have?

Q1) Rewrite 0.8 = 0.4*2,
(0.4) ^4 / (0.4) ^5 * (2^5)
Simplifying it, 1 / (32*0.4) = 1 / 12.8

Q2) Since the amount increased by 7.2%, we know that majority of the funds was invested in higher interest rate.
Total amount invested = 50K. Amount invested in X be x and Y be 50K-x.
Simple interest = p*n*r/100.
(50,000*1*7.2)/100 = (x*1*6) / 100 + ((50,000-x) * 1 * 8) / 100.

Solving for x = 20,000

Q3) For sum to be even, all four integers can be odd.
For product to be even, atleast one should be even. However if only one is even then sum will be odd.
For both sum and product to be even, maximum odd integers is 2 out of 4

o+o=e
e+o=o
e+e=o

o*o=o
o*e=e

Maximum # of odd integers can be 2.

Please post OA

ihategmat wrote:Problem 1:
(.8)^-5 / (.4)^-4 =

Problem 2:
Account X interest rate = 6%
Account Y interest rate = 8%
The total invested in these accounts was $50,000 and it increased 7.2%
How much was invested in Account X?

Problem 3:
There are 4 integers. There sum and product is even. What is the max odd numbers you can have?

Hi,
For the benefit of everyone, pls post the question in its entirety along with the 5 choices. Often we can learn as much from the wrong answers as from the right ones.

Thanks
-Vittal