Probability Question help help

Question

Hannah is taking a 6-item examination. Let her score be denoted by the variable X. Each item is worth 5 points. The exam is graded under the right-minus-wrong rule, which means incorrect and blank items are given a deduction of 5 points per item. Construct the probability mass function for X.

Answer 1

Correct answers, Score, Weight (C k of 6 where k is the # of correct answers (6!/(k!(6-k!)))

0 -30 1

1 -20 6

2 -10 15

3 0 20

4 10 15

5 20 6

6 30 1