Ms. Martino always gives a very easy 10-question quiz in the first week of her classes. Over the years, the number of questions that students answer correctly on these quizzes has been strongly skewed to the left with a mean of 9 correct answers and a standard deviation of about 2.5 correct answers.

Suppose we took random samples of 4 students and calculated -x as the sample mean number of questions that the students answered correctly. We can assume that the students in each sample are independent.

What would be the shape of the sampling distribution of -x?