Answer:
9
Step-by-step explanation:
cross multiply 7/63 by 1/x
so, multiply 7 by x and 63 by 1
you get 63=7x
divide by 7 on both sides and you get 9
Answer:
X^2 -4
Step-by-step explanation:
Not entirely sure but would u just expand the brackets. As this is a difference between 2 squares the answer should be correct but it not sure.
Answer:D
Step-by-step explanation:
Round 295 to 300. Then round $8.95 to $9. multiply 300 by 9. Then subtract 400. You have your answer!
The height is: 7.5 inches. Since the terrarium is 14.5 inches in total, and the width is 7 inches, the remaining inches makes up the height and that is 7.5.
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
