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:
9 tables
Step-by-step explanation:
All we have to do is see how many time 6³/₄ ft. can fit in 60³/₄ ft. through division.
60 ³/₄ ÷ 6 ³/₄ =
²⁴³/₄ ÷ ²⁷/₄ =
²⁴³/₄ × ⁴/₂₇ =
²⁴³/₂₇ =
9 tables
Answer:
$27.59
Step-by-step explanation:
You multiply 30 dollars by 0.85 (1-0.15, with the 0.15 being for the 15 percent off). Which gets you to $25.50, and you then multiply it by 1.082 (the 1.082 being the tax, and the .082 part equating to the 8.2% tax percentage).
When you are finding the area, you multiply the length x the width. So for example, we have a rectangle that the length is 6 feet and the width is 4 feet. So, first of all we multiply 6x4= 24. Since its area don't forget it is Square Feet (or any other type of measurement).
Hope it helps!
