class intervals

An investigation was done to examine the proportion of male teenagers who smoke. From a pilot study, it was found that out of 150 males, 40 smoked. Find the 99% confidence interval of the true proportion of teenagers who smoke. => 16.05% < p < 37.95% or 17.6% < p < 36.4% or 21..

The lengths (in miles) of 10 rivers taken randomly are shown here. Find the 98% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed. 1928 1728 1234 1110 1000 2340 1995 2005 1947 1857 => 82215 < σ 2 < 853095 ; 287 < &..

In the given stem-and-leaf plot, find how many data values are greater than 102, from the intervals 80 - 89, 90 - 99, 100 - 109, and 110 - 119. => 4 or 5 or 3 or 2..

Identify the interval level of data. I. height II. nationality III. age IV. IQ V. time => II only or IV only or V only or III, IV and V only..

A restaurant owner wishes to find the 99% confidence interval of the mean number of visitors to the restaurant each day. How large the sample must be if he wants to be accurate within 10 persons? A previous study showed that the standard deviation of the visitors was 26 persons. => 45 or ..

Find the 95% confidence interval for the variance of the ages of players in a basketball team if a sample of 12 players has a standard deviation of 2 years. Assume the variable is normally distributed. => between 2 and 10 or between 2 and 13 or between 2 and 14 or between 2 and 12..

A vehicle travels 118 miles in 3 hours. What is its average velocity over the entire 3 hours time interval? => 39.33 miles/hour or 354 miles/hour or 115 miles/hour or 0.03 miles/hour..

Find the 95% confidence interval for the mean number of people working in night shifts in different parts of the cities in a particular state. A sample of 35 selected cities is shown. => 920.9 < μ < 1,511.4 or 930.905 < μ < 1,501.375 or 925.9 < μ < 1,550.4 or 91..

A sample of 30 RAM chips was tested for the average access time. The standard deviation was found to be 2 nanosec. Find the 90% confidence interval for the true standard deviation. Assume that the variable is normally distributed. => between 1.7 and 2.6 or between 1.6 and 2.5 or between 1..

The number of miles per hour driven by a sales person on 14 different days is listed here. What is the point estimate for the mean? Find the 95% confidence interval of the mean for the average miles per hour. => 32.3 and 29.5 < μ < 35.1 or 31.5 and 31 < μ < 34 or 30.13 a..