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 Length of third side is 52 units.
Step-by-step explanation:
Given:
Length of First side = 48
Length of second side = 20
Also given the angle between them is 90°.
Hence we can say figure shown is a right angled triangle.
For finding the third side we can use Pythagoras theorem which states that;
"If a triangle is right angled then, the Square of the hypotenuse is equal to sum of the square of the other two sides."

Hence substituting the values we get;

Now taking Square root on both side we get;

Hence Length of Third side is 52 units.
Answer:

Step-by-step explanation:
We are given polynomial as

and it is divided by x=3 or x-3
we can use synthetic division
so, we got
Remainder =5
Quotient is


we can write as

The expression in company B represents that is is in arithmetic progression where first term is 42000 and common difference is 1800 . So we have to use the formula of sum of n terms which is

Where a is the first term, n is the nth term, d is the common difference
On substituting there values,we will get

= 15(84000+52200) = 15*136200 =2043000
And for company A, it is

Difference between them =2043000-2002500= 40500
So the correct option is the second option .