1. A business wants to estimate true mean annual income of its customers. The business needs to be in $500 of true mean. The business estimates true population standard deviation is around $2,300. If the confidence level is 95%, find out the required sample size in order to meet wanted accuracy.
2. The area under the normal curve with mu = 15 and sigma = 2 is
A) none of these
B) 0
C) 2
D) 1