+171 An engineer invested $10,000 in a six-month savings certificate that paid a simple annual interest rate of 12%. After six months, she invested the total value of her investment in another six-month certificate. After six more months, the investment was worth $11,130. If the annual interest rate of the second certificate is r% then what is r?
+37146 10000 + 10000 x (.12) x 6mos/ 12mos = amount after 6 months at 12% simple = 10600
10600 +10600 x (r) x 1/2 = 11130 after six more months at rate, r
r = .1 ~~ = 10%
