Chapter 1, Problem 30R

Q3. The distribution for the working lifetime of light bulbs, manufactured in a company, is found to be normally distributed with a mean of 1450 hours and a standard deviation of 60 hours. a) In this distribution, find the life time of a lightbulb whose z-score is -1.8? b) Which percentage of lightbulbs have life time less than 1400 hours? c) Which percentage of lightbulbs have life time greater than 1500 hours? d) Which percentage of lightbulbs have life time between 1420 to 1500 hours?

Q4. Considering the following two normal distributions A and B, which statement (or statements) is correct? a) Mode of the distribution A is larger than that of distribution B. b) SD of the distribution B is larger than that of distribution A. c) Mean of the distribution A is smaller than that of distribution B. d) A data item with z-score of -1 falls between 20 to 30 in distribution A. e) A data item with z-score of +1 falls between 10 to 20 in distribution B. A 0 10 20 30 40 40 50 60 00 10 70 B 80 90 100

Q1. A traffic camera recorded number of red cars going through the intersection at 16th Ave N and Centre St. each day over 7 days was: 32 30 24 30 36 38 27 a) Calculate the mean, mode, range and median of the data set above. c) Calculate the standard deviation of this data set. S