The following data shows the average time span of international phone calls by a

sample of 15 executives of a company having operations overseas:

time in (minutes)

12.0 15.0 16.3 13.2 12.6 18.2 8.7 13.5

16.9 11.3 15.4 16.2 12.6 10.5 9.6 6.0

an approximate 95% confidence interval for the average time span of calls is

(a) 11.244 to 14.756

(b) 12.344 to 15.856

(c) 10.564 to 14.876

(d) 12.831 to 16.667

(e) 13.453 to 15.887

Lems1. the following data set represents the scores on intelligence quotient(iq) examinations of 40 sixth-grade students at a particular school: 114, 122, 103, 118, 99, 105, 134, 125, 117, 106, 109, 104, 111, 127,133, 111, 117, 103, 120, 98, 100, 130, 141, 119, 128, 106, 109, 115,113, 121, 100, 130, 125, 117, 119, 113, 104, 108, 110, 102(a) present this data set in a frequency histogram.(b) which class interval contains the greatest number of data values? (c) is there a roughly equal number of data in each class interval? (d) does the histogram appear to be approximately symmetric? if so,about which interval is it approximately symmetric?