QUESTION 7 0.5 points Savo Answer Question B3: Suppose that a histogram of the repair costs in the sample showed a mound-shaped distribution. Is this important for the validity of the confidence interval or not? Why? a. It is important. For any confidence interval to be valid, the sample must have a mound-shaped distribution. b. It is not important. Since the mean of the sample is large, the sampling distribution of x-bar will be approximately normal, even if the population's distribution is not. c. It is not important. Since the confidence interval is based on a t-distribution, a mound-shaped distribution for the sample is not necessary. )d. It is important. Since the sample size is small, we need to assume that the distribution of repair costs is approximately normal. The mound-shaped distribution provides some support for that assumption