Question

The SAT is standardized to be normally distributed with a mean µ = 500 and a standard deviation σ = 100. What percentage of SAT scores falls:_____.
a. Between 500 and 600? the answer says 34.13% <<< how do you get to that???
b. Between 400 and 600?

Answer 1

Answer:

34.134%

68.268%

Step-by-step explanation:

Given that:

Mean (m) = 500

Standard deviation (s) = 100

Percentage between 500 and 600

P(500 < x < 600)

P(x < 600) - P(x < 500)

Z = (x - m) / s

P(x < 600)

Z = (600 - 500) /100 = 1

P(x < 500)

Z = (500 - 500) / 500 = 0

P(Z< 1) - P(Z < 0)

0.84134 - 0.5

= 0.34134

= 0.34134 * 100%

= 34.134%

B.) Between 400 and 600

P(x < 400)

Z = (400 - 500) /100 = - 1

P(x < 600)

Z = (600 - 500) / 500 = 1

P(Z< 1 ) - P(Z < - 1)

0.84134 - 0.15866

= 0.68268

= 0.68268 * 100%

= 68.268%