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Answer:
Four less than an unknown value E)
Quotient of a variable and four B)
Some number to the power of four A)
Four times an unknown value D)
Four more than some number C)
Step-by-step explanation:
Let's analyze each statement separately:
- Four less than an unknown value --> this means that we have to subtract 4 to an unknown value. Calling the unknown value, it means we have to write
- Quotient of a variable and four --> this means we have to divide a variable by 4. Calling the unknown variabl, it means we have to write
- Some number to the power of four --> this means that we have to write the power of a number, in the form , where m in this case is equal to 4. Calling
the unknown number, it means we have to write
- Four times an unknown value --> this means that we have to multiply an unknown value by 4. Calling our unknown values, we have to write
- Four more than some number --> this means we have to add 4 to an unknown number. Calling the unknown number, it means we have to write
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