Answer:
$613.80
Step-by-step explanation:
7% of 660 = 0.07 × 660 = 46.2
660 - 46.2 = 613.80
For a two-tailed test we need to halve 0.01, giving 0.005. Then we need to sutract 0.005 from 0.5, giving 0.5 - 0.005 = 0.495. Looking up the p value of 0.495 in an inverse normal probability table we obtain the value z = 2.5758. Therefore the critical values are -2.5758 and 2.5758.
You need 250-116=$134. At $15 a day this is 134/15=8.93 days approx. After 9 days you will reach $251.