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
Given:
The recipe calls for 0.5 quart of milk and 2.5 cups of flour.
She has 
quart of milk and 
cups of flour.
To find:
Whether she have the correct amount of milk and flour to make the pancakes from the recipe.
Solution:
Required Milk = 0.5 quart
Milk she has = 
quarts
Clearly, 0.375 < 0.5.
Required Flour = 2.5 cups
Flour she has = 
cups
Clearly, 2.25 < 2.5
Since, the amount of milk and flour she has is less than the required amount, therefore she does not have the correct amount of milk and flour to make the pancakes from the recipe
Answer:
-11s^3 -4
Step-by-step explanation:
( -22s^4t -8st) /2st
Separate into parts
-22s^4t / 2st -8st /2st
-11 s^3 -4
1. Variables and constants
2. -2y + -4
3. y
Hope this helped
It will take Mr. Jenkins 1 hr and 20 minutes to cut all the grass.
To know how long it will take Mr. Jenkins to cut all the grass, get the total area of the lawn and divide it by the rate Mr. Jenkins cut the grass.
The area of the lawn can be calculated using the formula for the area of a rectangle given by:
A = l x w
where l is the length and w is the width.
Using this formula, the grass lawn that is 24 m wide and 30 m long has an area of:
A = l x w
where
l = 30 m
w = 24 m
A = 30 m x 24 m
A = 720 m^2
Meanwhile, the time it will take Mr. Jenkins to cut the grass lawn with an area of 720 m^2 can be computed using the rate.
amount = rate x time
720 m^2 = 9 m^2/minute x t
t = 720 / 9
t = 80 minutes = 1 hr 20 minutes
To know more about rate, visit brainly.com/question/24950565.
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