At the beginning of the year, David estimated he would save $8 * 10^3. David saved $2 * 10^4 for the year. Approximately how many times greater or less were his savings than his estimate? A. 2.5 times less.
B. 0.4 times less.
C. 2.5 times greater.
D. 0.4 times greater.

A. find the power of the test, when the null hypothesis assumes a population mean of mu = 450, with a population standard deviation of 156, the sample size is 5 and the true mean is 638.47 with confidence intervals of 95 b. find the power of the test, when the null hypothesis assumes a population mean of mu = 644, with a population standard deviation of 174, the sample size is 3 and the true mean is 744.04 with confidence intervals of 95% c. find the power of the test, when the null hypothesis assumes a population mean of mu = 510, with a population standard deviation of 126, the sample size is 10 and the true mean is 529.44 with confidence intervals of 95