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
Answer:
The coordinates of the vertex is (6,4).
Step-by-step explanation:
The vertex is the highest or lowest point on the parabola (curved line).
The LCM of 4,8,14 is 56
M of 4 are 4,8,12,16,20,24,28,32,36,40,44,48,52,56
M of 8 are 8,16,32,48,56,64
M of 14 are 14,28,42,56
I hope this helps you
Because the ratio of women to children is 10:1, double the ratio of men to women so the women are both 10:
Men to women becomes 8:10
Now total the 3 ratios: 8 for men, 10, for women and 9 for children:
8 + 10 + 9 = 27
Divide total people by that number:
270/27 = 10
Multiply 10 by each ratio:
Men = 8 * 10 = 80
Women = 10 * 10 = 100
Children = 9 *10 = 90
There is 80 men.
