Answer:
a) Option C) The score was 2.49 standard deviations higher than the mean score in the class.
b) 2.3%
Step-by-step explanation:
a) We are given that the distribution of test grades is a bell shaped distribution that is a normal distribution.
Formula:


Option C) The score was 2.49 standard deviations higher than the mean score in the class.
b) The z-score for a particular score is -2.
We have to evaluate
P(z < -2)
Calculating the value from normal z-table.

Thus, 2.3% of of the class scored lower than my friend.
Answer:
Step-by-step explanation:
cross multiply
-6 * 12 = 2 + z
-72 = z + 2
z = -2-72 = -74
Answer:
1:3
Step-by-step explanation:
it is a bit easy to get it out of decimal ratio, so multiply it by 10, which gives you 4:12, so now you have a bigger answer to work with, you can divide 12 by 4, which gives you 3, and a ratio of 1:3
9/36 in the simplest form is 1/4