Suppose you are working with a data set that is normally distributed, with a mean of 300 and a standard deviation of 47. Determine the value of x from the following information. (Round your answers and z values to 2 decimal places.) (a) 80% of the values are greater than x. (b) x is less than 14% of the values. (c) 23% of the values are less than x. (d) x is greater than 52% of the values
Accepted Solution
A:
Answer: (a) x = 260.52(b) x = 249.24
(c) x = 265.22
(d) x = 297.65 Step-by-step explanation:Here,
Mean = [tex]\mu[/tex] = 300
Standard deviation = [tex]\sigma[/tex] = 47
(a)
Using standard normal table,
P(Z > z) = 80%
1 - P(Z < z) = 0.8
P(Z < z) = 1 - 0.8
P(Z < -0.52) = 0.2
z = -0.84
Using z-score formula,
x = z × σ + μ
x = -0.84 × 47 + 300 = 260.52
(b) Using standard normal table,
P(Z < z) = 14%
P(Z < -1.08) = 0.1
4
z = -1.08
Using z-score formula,
x = z × σ + μ
x = -1.08 × 47 + 300 = 249.24
(c)
Using standard normal table,
P(Z < z) = 23%
P(Z < -0.74) = 0.243
z = -0.714
Using z-score formula,
x = z × σ + μ
x = -0.74 × 47 + 300 = 265.22
(d) Using standard normal table,
P(Z > z) = 52%
1 - P(Z < z) = 0.52
P(Z < z) = 1 - 0.52
P(Z < -0.25) = 0.4
8
z = -0.05
Using z-score formula,
x = z × σ + μ
x = -0.05 × 47 + 300 = 297.65