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
I'm pretty sure that there are two statements which are true: b. At the conclusion of the story, Charles Waddell Chesnutt wants readers to see the redeeming qualities in Mr. Ryder. and c. The wife of Mr. Ryder's youth could never be a member of his exclusive society.
Answer: AC=12 cm
Step-by-step explanation:
To solve this problem you must apply the law of sines, as you can see below:
Where:
a=13
A=85.2°
B=71.6°
Therefore, you must solve for b, then, you obtain that the lenght AC asked in the problem above is:
Answer:
length=4
width=30
Step-by-step explanation:
length=x
width=8x-2
(8x-2)*2+2x=68
16x-4+2x=68
18x=72
x=4 (Length)
4*8=32, 32-2=30(width)
Answer:
35°
Step-by-step explanation:
The central arc is equal to the arc that subtends it, then
arc AC = 75° and
BC = AC - AB = 75° - 40° = 35°
