Answer:
0.13% of students have scored less than 45 points
Step-by-step explanation:
Problems of normally distributed samples can be solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:

About what percent of students have scored less than 45 points?
This is the pvalue of Z when X = 45. So



has a pvalue of 0.0013
0.13% of students have scored less than 45 points
Answer:
1/4 n - 3.
Hope this helps, sorry if it doesn't.
I=prt
20=p X .05 X 5
20 = p X .25
20/.25 = p
80 = p
She started with $80
Answer:
2x-5= -20
move -5 to the other side
sign changes from -5 to 5
2x-5+5= -20+5
2x= -15
divide by 2 for both sides
2x/2= -15/2
cross out 2 and 2, divide by 2 and 2 and then becomes x
x= -15/2