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:
Vertex: (-2,1)
X - intercepts: There are no x intercepts
Y - intercept: (0,2)
Step-by-step explanation:
Just look at the graph, it says it all.
Answer:
32
Step-by-step explanation:
So the order of the points is: GHJK
GH = x+10 =JK
HJ=8
JK=2x-4
JK = x+10=2x-4
x+10=2x-4
10+4=2x-x
x=14
GH= 14+10 =24
GJ = GH +HJ = 24+ 8=32
Answer:
The first choice
Step-by-step explanation:
Multiplyil by 6 to get 4y - 1 =21
