Answer:
Mean = 78.2
Standard deviation = 5.8
Step-by-step explanation:
Mathematically z-score;
= (x-mean)/SD
From the question;
12% of test scores were above 85
Thus;
P( x > 85) = 12%
P(x > 85) = 0.12
Now let’s get the z-score that has a probability of 0.12
This can be obtained from the standard normal distribution table and it is = 1.175
Thus;
1.175 = (85 - mean)/SD
let’s call the mean a and the SD b
1.175 = (85-a)/b
1.175b = 85 - a
a = 85 - 1.175b ••••••••(i)
Secondly 8% of scores were below 70
Let’s find the z-score corresponding to this proportion;
We use the standard normal distribution table as usual;
P( x < 70) = 0.08
z-score = -1.405
Thus;
-1.405 =( 70-a)/b
-1.405b = 70-a
a = 70 + 1.405b ••••••(ii)
Equate the two a
70 + 1.405b = 85 - 1.175b
85 -70 = 1.405b + 1.175b
15 = 2.58b
b = 15/2.58
b = 5.81
a = 70 + 1.405b
a = 70 + 1.405(5.81)
a = 78.16
So mean = 78.2 and Standard deviation is 5.8
Use the formula:
Radio= r, Height= h
V= 3.14xrx2h
r =25, h=31
V= 3.14 x 25 x 2 (31) =. 4867
V= 4867 cubic inches
Step-by-step explanation:
Answer:
Step-by-step explanation:
Given
Represent point A as thus;
Required
Determine the new position of A, when rotated counterclockwise
The new position will be denoted as A'
When a point is rotated counterclockwise, we start by switching the positions of x and y as follows:
Then, y is negated to give A'
A. y=180-15m
m is the number of months. 180 is the amount owed after the down payment was made.
B. X intercept (12,0)
Y intercept (0,180)
X intercept is the number of months until the tv is paid off. The y intercept is the amount owed after the down payment is made. How much they will be making payments on.
32. 5x + 15
