Question

Paul Hilseth plans to invest $4,780. Find the interest rate required for the fund to grow to $5,138.50 in 15 months.

A 150-day loan for $12,000 has interest of $375.
Find the rate to the nearest tenth of a percent.

Bill earned $40 interest on a $6,400 deposit in an account paying 6%.
Find the number of days that the funds were on deposit. Round to the nearest day

Answer 1

5.96%

7.6%

38 days

Explanation:

15 months = 1.25 years

5138.5 = 4780 × R^1.25

R^1.25 = 43/40

1.25 lgR = lg(43/40)

lg R = 0.0251267714

R = 1.059562969

R - 1 = 0.059562969

Interest: 5.96%

(150/365) × (r/100) × 12000 = 375

r/100 = 0.0760416667

r = 7.6%

40 = (n/365) × (6/100) × 6400

(n/365) = 5/48

n = 38.02083333 = 38