Answer:
x6
Step-by-step explanation:
you are trying solve for x factor
You have posted 2 separate questions here. Please, next time, separate them with a blank line:
<span>A circle has an area of 81 3.14 units . what is the diameter in terms of 3.14?
I'd prefer you write this as
"</span><span>A circle has an area of 81 pi units . what is the diameter in terms of pi?
Area of a circle = A = pi*r^2. Note that r= diameter / 2. Here, the area is 81 pi square units, or 9^2 * pi square units, which means that the radius is 9 units. The diameter is then 2(9 units) = 18 units.
Your second question, separated from the first, is:
"</span><span>a circle has an area of 81 Pi square units what is the diameter of the circle?"
</span><span>
Use the following formula or formulas: d = 2*r; A = pi*r^2; A = pi*(d/2)^2. Find r first, and then find d.
</span>
Answer: When they take my phone I take it back when there not looking
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
