Question

Question 12 (1 point)

For problems 12-15 :In a study of facial behavior people in a control group are timed as to the duration of eye contact that they make during a 5-minute period. Their times are normally distributed with a mean of 180.0 seconds and a standard deviation of 55 seconds. Use the 68-95-99.7 rule to find the indicated quantity. (Sketch a picture if you need!)

  Find the percentage of participants with times between 70 and 290 seconds.?

Find the percentage of times greater than 15 seconds?

Find the percentage of times less than 125 seconds.?

Find the percentage of times between 70 and 180 seconds.?

Answer 1

12)
Solution :

Using Empirical rule,

P( - 1< X < + 1) = 68%

P( - 2< X < + 2) = 95%

P( - 3< X < + 3) = 99.7%

(a)

P(70 < X < 290) = 95%

(b)

P(X > 15) = 99.85%

(c)

P(X < 125) = 16%

(d)

P(70 < X < 180) = 47.5%