Question

Suppose that the amount spent by students on textbooks this semester has approximately a normal distribution. The mean amount spent was $300 and the standard deviation is $100. Which choice BEST completes the following sentence? About 68% of students spent between...

A) 300 and 400

B) 200 and 400

C) 100 and 500

D) 266 and 334

Answer 1

Solution :

mean = = 300

standard deviation = = 100

Using Empirical rule,

P( - 1 * < + 1 * 0 = 68%

P(300 - 1 * 100 < X < 300 + 1 * 100) = 68%

P(200 < X < 400) = 68%

About 68% of students spent between 200 and 400 .

Option B)