Answer:
A) 34.13%
B) 15.87%
C) 95.44%
D) 97.72%
E) 49.87%
F) 0.13%
Step-by-step explanation:
To find the percent of scores that are between 90 and 100, we need to standardize 90 and 100 using the following equation:

Where m is the mean and s is the standard deviation. Then, 90 and 100 are equal to:

So, the percent of scores that are between 90 and 100 can be calculated using the normal standard table as:
P( 90 < x < 100) = P(-1 < z < 0) = P(z < 0) - P(z < -1)
= 0.5 - 0.1587 = 0.3413
It means that the PERCENT of scores that are between 90 and 100 is 34.13%
At the same way, we can calculated the percentages of B, C, D, E and F as:
B) Over 110

C) Between 80 and 120

D) less than 80

E) Between 70 and 100

F) More than 130

Answer:

Step-by-step explanation:



Answer:
x = 9
Step-by-step explanation:
7x = 63
Divide each side by 7 to isolate x
7x/7 = 63/7
x = 9
Answer:
X= -3;
Y=78
Step-by-step explanation:
A: X+Y=75
B: 10X+Y=48
B-A: (10X+Y)-(X+Y)=48-75
10X+Y-X-Y= - 27
9X=-27
X= -3;
Now
A is : -3+Y=75
Y=75+3=78