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1. Warmups 2. Check HW. Find (a) the simple interest and (b) the amount paid for the loan. $12,000 borrowed at 4.9% for 4 years. $18,500 borrowed at 19.9% for 180 months. 4.4 Continued: Working backwards to find r or t in I = Prt. Find the interest rate.
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1. Warmups 2. Check HW Find (a) the simple interest and (b) the amount paid for the loan. • $12,000 borrowed at 4.9% for 4 years. • $18,500 borrowed at 19.9% for 180 months.
Find the interest rate How to: Normally in I =Prt, we multiply to find the interest. So, when working backwards, we divide. Example 1: Find the simple interest rate if I=$116.25, P=$1550, and t=9 months.
Find the time. Divide! Example 2: Find the time if the interest earned is $45.60, the principal is $2400, and the interest rate is 3.8%.