Question

Question 12 (1 point) Let's look at grades again. Let's say that the grades for a particular test are Normally- Distributed with mean=80 and standard deviation = 7. What's the probability that a random student has scores a grade of 70 or below? Op= 2432 Op=.0485 Op=.0766 Op=.1254

Answer 1

Let , $X\to N(\mu=80,\sigma=7)$

Now ,

$P(X\leq 70)=P(\frac{X-\mu}{\sigma}\leq \frac{70-80}{7})=P(Z\leq -1.4286)$

; The Excel function is , =1-NORMDIST(1.4286,0,1,TRUE)

- Φ -1.4286) = 1 – Φ(1.4286) = 0.0766