Scores of gre are normally distributed with a mean of 505 and standard deviation of 146. Use the 68-95-99.7 rule to find the percentage of people taking the test who score between 213 and 797

95%

Step-by-step explanation:

The 68-95-99.7 rule to find the percentage of people is also know as the empirical rule.

The empirical rule formula states that:

68% of data falls within 1standard deviations from the mean - between μ – σ and μ + σ .

95% of data falls within 2 standard deviations from the mean - between μ – 2σ and μ + 2σ .

99.7% of data falls within 3 standard deviations from the mean - between μ - 3σ and μ + 3σ .

From question:

Mean (μ) = 505

Standard deviation (σ) = 146

Hence, we are to find the number of standard deviation which is represented as x

The score is between 213 and 797

μ - xσ

= 505 - 146x = 0

= 505 - 146x = 213

146x = 505 - 213

146x = 292

x = 292/146

x = 2

μ + xσ

505 +146x = 797

146x = 797 - 505

146x = 292

x = 292/146

x = 2

Hence, the percentage falls within 2 standard deviation from the mean.

Thus, from the formula above:

95% of data falls within 2 standard deviations from the mean - between μ – 2σ and μ + 2σ .

Therefore, the percentage of people taking the test who score between 213 and 797 is 95%

step-by-step explanation:

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.