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Last year, Carmen had $20,000 to invest. She invested some of it in an account that paid 7% simple interest per year, and she invested the rest in an account that paid 6% simple interest per year. After one year, she received a total of $1290 in interest. How much did she invest in each account?

User Serge C
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1 Answer

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Last year, Carmen had $20,000 to invest. She invested some of it in an account that paid 7% simple interest per year, and she invested the rest in an account that paid 6% simple interest per year. After one year, she received a total of $1290 in interest. How much did she invest in each account?

Let

x ------> amount invested an account that paid 7% simple interest per year

20,000-x ------> amount invested an account that paid 6% simple interest per year

Remember that

The formula to calculate the simple interest is equal to

I=P(rt)

in thus problem we have

r1=7%=0.07

r2=6%=0.06

t=1 year

P1=x

P2=20,000-x

I1+I2=1290

x(0.07)(1)+(20,000-x)(0.06)(1)=1,290

solve for x

0.07x+1,200-0.06x=1,290

0.01x=1,290-1,200

0.01x=90

x=9,000

therefore

The amount invested an account that paid 7% simple interest per year was $9,000

and

The amount invested an account that paid 6% simple interest per year was $11,000

User Bojtib
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