Answer:
20
Step-by-step explanation:
We can set up a percentage proportion to find the value of x.

Now we cross multiply:

Hope this helped!
Answer:
3. a
4. d
5. a
Step-by-step explanation:
Let X be the national sat score. X follows normal distribution with mean μ =1028, standard deviation σ = 92
The 90th percentile score is nothing but the x value for which area below x is 90%.
To find 90th percentile we will find find z score such that probability below z is 0.9
P(Z <z) = 0.9
Using excel function to find z score corresponding to probability 0.9 is
z = NORM.S.INV(0.9) = 1.28
z =1.28
Now convert z score into x value using the formula
x = z *σ + μ
x = 1.28 * 92 + 1028
x = 1145.76
The 90th percentile score value is 1145.76
The probability that randomly selected score exceeds 1200 is
P(X > 1200)
Z score corresponding to x=1200 is
z = 
z = 
z = 1.8695 ~ 1.87
P(Z > 1.87 ) = 1 - P(Z < 1.87)
Using z-score table to find probability z < 1.87
P(Z < 1.87) = 0.9693
P(Z > 1.87) = 1 - 0.9693
P(Z > 1.87) = 0.0307
The probability that a randomly selected score exceeds 1200 is 0.0307
Answer:
X=3
Step-by-step explanation:
What you have to do is minus 2 from 11 and you get 9
Now divide 3 into 9 and you get 3
x=3 you can also plug 3 for x to see if the equation is right
5) k/35=3/7 : cross multiply
35*3=7k : simplify
105=7k : divide both sides of the equation by 7
k=15
6) 3/t=18/24 :cross multiply
18t=24*3 :simplify
18t=72 : divide both sides of the equation by 18
t=4
7) 10/8.4 = 5/m :cross multiply
10m=5 * 8.4 :simplify
10m=42 :divide both sides by 10
m=4.2