A consumer group has determined that the distribution of life spans for…

A consumer group has determined that the distribution of life spans for gas ranges (stoves) has a mean of
years and a standard deviation of
years. The distribution of life spans for electric ranges has a mean of
years and a standard deviation of
years. Both distributions are moderately skewed to the right. Suppose we take a simple random sample of 35 gas ranges and a second SRS of 40 electric ranges. Which of the following best describes the sampling distribution of
, the difference in mean life span of gas ranges and electric ranges?
a. Mean
years, standard deviation
years, shape: moderately right-skewed.
b. Mean
years, standard deviation
years, shape: approximately Normal.
c. Mean
years, standard deviation
years, shape: moderately right skewed.
d. Mean
years, standard deviation
years, shape: approximately Normal.
e. Mean
years, standard deviation
years, shape: moderately right skewed.