SOLUTION: The simple interest (Is)in a savings account varies jointly as the Principal (P) and the time (T). After 3 months, 8000 pesos deposit earned 100 pesos in interest. How much will a

Question 588227: The simple interest (Is)in a savings account varies jointly as the Principal (P) and the time (T). After 3 months, 8000 pesos deposit earned 100 pesos in interest. How much will a 10,000 pesos principal earn in 5 months?
This is about Variation. But this kind of variation is a joint variation. Its formula to solve it is y=kxz.
I've tried to find fist the k and k is equal to 1/240.
But, when I'm finding the Is in the second question, it is bigger :| Can you help me to answer?
Thank you so much in advance :)
-Karen
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
The simple interest (Is)in a savings account varies jointly as the Principal (P) and the time (T). After 3 months, 8000 pesos deposit earned 100 pesos in interest. How much will a 10,000 pesos principal earn in 5 months?
This is about Variation. But this kind of variation is a joint variation. Its formula to solve it is y=kxz.
.
You are correct.
k = 1/240
AND
Is for 10,000 pesos in 5 months SHOULD be bigger.
.
How much will a 10,000 pesos principal earn in 5 months?
Is = (1/240)PT
Is = (1/240)(10000)(5)
Is = (1/24)(1000)(5)
Is = (1/24)(5000)
Is = 5000/24
Is = 208.33 pesos

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