Question

lYou invested S8000 between two accounts paying 4% and 8% annual interest, respectively if the total interest earned for the year was $520, how much was invested at each ratė? was invested at 4% and was invested at 8% Enter your answer in the edit fields and then click Check Answer All parts showing Clear All Check Answer

Answer 1

$3000 was invested at 4% and was $5000 invested at 8%

Step-by-step explanation:

The formula for calculating simple interest id expressed as;

I = I1+I2

I1 and I2 are the interest earned on both accounts'

Since I =PRT/100

520 = P1R1T1/100 + P2R2T2/100

P is the principal

R is the rate

T is the time

520 = P1(4)(1)/100 + P2(8)(1/100)

520 = (4P1+8P2)/100

4P1+8P2 = 520 *100

4P1+8P2 = 52,000 ......1

SInce the total amount invested is $8,000, hence;

P1 + P2 = 8000 .... 2

Solve 1 and 2 simultaneously;

4P1+8P2 = 52,000 ......1 ..... * 1

P1 + P2 = 8000 .... 2 .... * 4

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4P1+8P2 = 52,000

4P1 + 4P2 = 32000

Subtract both equatons;

8P2 - 4P2 = 52000 - 32000

4P2 = 20000

P2 = 20000/4

P2 = 5000

Recall that P1 + P2 = 8000

P1 = 8000 - P2

P1 = 8000 - 5000

P1 = 3000

Hence $3000 was invested at 4% and was $5000 invested at 8%