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:
D. The system is in echelon form.
Step-by-step explanation:
Check attachment
Justin buys 4 hot dogs ad 5 pop corn boxes at the baseball game.
<h3>Equation</h3>
Equation is an expression which is used to show the relationship between two or more variables and numbers.
Let x represent the number of hot dogs and y represent the boxes of popcorn.
Justin buys a total of 9 snacks. Hence:
He buys popcorn 3 less than twice as many hot dogs. Hence:
Solving equations 1 and 2 simultaneously gives:
x = 4, y = 5
Justin buys 4 hot dogs ad 5 pop corn boxes at the baseball game.
Find out more on equation at: brainly.com/question/13763238
<h2>Hello my friend.</h2>
The Pi value is approximately equal to 3.14.
<h2>I hope I have helped a lot.</h2>
Answer:
B) 628.32 cm cubed
Step-by-step explanation:
we know the formula to find the volume of a cylinder is π*r^2*h
where r is the radius and h is the height.
the equation would look like this
π*5^2*8
π*25*8
π*200
628.32 cm
