Your dad put $1,000 into a new bank account to save money for a family trip. He earned $18.75 in simple interest after 15 months. What is the annual interest rate? Use the formula: I = Prt.

Step one multiply

15 x 1,000

Step two divide

15000/18.75=?

I=PRT

T=time in hears

P=principal=amount you put

R=rate

so 15 momths=15/12=1.25 years

prinicipa 1000

interset=18.75

subsitute

18.75=1000 times R times 1.25

multiply

18.75=R times 1250

divide both sides by 1250

0.015=R

R=rate in percent

percent means parts ot of 100

0.015/1 times 100/100=1.5/100=1.5%

so annual interest rate=1.5%