Please help with at least one question I’m really stressed
Answer:
0.9007 is the probability that a student scored below 86 on this exam.
Step-by-step explanation:
We are given the following information in the question:
Mean, μ = 77
Standard Deviation, σ = 7
We are given that the distribution of examination grades is a bell shaped distribution that is a normal distribution.
Formula:

a) P(student scored below 86)
P(x < 86)
Calculation the value from standard normal z table, we have,

0.9007 is the probability that a student scored below 86 on this exam.
Answer: D
Explanation: For this problem you can substitute f(x) and x for 21 and -6 respectively.
Thus, we have 21=-3(-6)+4