Exam 10: Introduction to Statistics

A company installs 5000 light bulbs, each with an average life of 500 hours, standard deviation of 100 hours, anddistribution approximated by a normal curve. Find the approximate number of bulbs that can be expected to last thespecified period of time. -Between 500 hours and 675 hours

Assume the distribution is normal. Use the area of the normal curve to answer the question. Round to the nearest whole percent. -At a local market, the average weekly grocery bill is $\$ 57.85$ with a standard deviation of $\$ 14.25$ . What is the lowest amount spent by the upper $25 \%$ of market customers?

Solve the problem. -The stem and leaf plot depicts the average weight (in pounds) of all four year olds receiving their annual influenza vaccine from the local health clinic. How many children weighed more than 40 pounds at the time of their influenza vaccine?

In a certain distribution, the mean is 50 with a standard deviation of 6 . Use Chebyshev's theorem to tell the probabilitythat a number lies in the following interval. Round your results to the nearest whole percent. -Less than 26 or more than 74

At one high school, students can run the 100-yard dash in an average of 15.2 seconds with a standard deviation of .9 seconds. The times are very closely approximated by a normal curve. Find the percent of times that are indicated. Round to the nearest whole percent. -Less than 15.2 seconds

A company installs 5000 light bulbs, each with an average life of 500 hours, standard deviation of 100 hours, anddistribution approximated by a normal curve. Find the approximate number of bulbs that can be expected to last thespecified period of time. -Less than 500 hours

Solve the problem. -If the life of a car engine, calculated in miles, is normally distributed, with a mean of 200,000 miles and a standard deviation of 18,000 miles, what should be the guarantee period if the company wants less than $2 \%$ of the engines to fail while under warranty?

A company installs 5000 light bulbs, each with an average life of 500 hours, standard deviation of 100 hours, anddistribution approximated by a normal curve. Find the approximate number of bulbs that can be expected to last thespecified period of time. -Between 290 hours and 540 hours

Describe the shape of the given histogram. -

Find the standard deviation. Round to the nearest tenth. - $43,39,33,88,66,43,86,74,49$

Solve the problem. Round to the nearest hundredth. -The table summarizes the total incomes in the year 2000 of the residents of a particular town. Only those residents with full-time employment are included. Estimate the mean income for fully employed residents of the town in 2000 .

Construct a-stem and leaf display for the given data table. - 11 32 60 18 63 24 41 21 34 29 45 16 55 48 52 34 59 13

Solve the problem. -Use the boxplot below from data for state and local community expenditures on police and fire protection. Is there greater variability in spending on police or fire protection?

Solve the problem. Round to the nearest hundredth. -Using the information in the table on home sale prices in the city of Summerhill for the month of June, find the mean for the grouped data.

Solve the problem. -Find the percent of the area under the standard normal curve between $\mathrm{z}=-1.68$ and $\mathrm{z}=1.68$ .

Assume the distribution is normal. Use the area of the normal curve to answer the question. Round to the nearest whole percent. -The mean monthly income of trainees at a local mill is $\$ 1100$ with a standard deviation of $\$ 150$ . Find the probability that a trainee earns less than $\$ 900$ a month.

Find the mean -The six Cane brothers spent $\$ 68.07, \$ 49.88, \$ 75.86, \$ 72.64, \$ 70.99$ , and $\$ 64.80$ on groceries. Find the mean grocery bill.

At one high school, students can run the 100-yard dash in an average of 15.2 seconds with a standard deviation of .9 seconds. The times are very closely approximated by a normal curve. Find the percent of times that are indicated. Round to the nearest whole percent. -At least 14.3 seconds

Construct a boxplot. -The test scores of 40 students are listed below. Construct a boxplot for the data set. 25 35 43 44 47 48 54 55 56 57 59 62 63 65 66 68 69 69 71 71 73 73 74 76 77 77 78 79 80 81 81 82 83 85 89 92 93 94 97 98

Find the standard deviation. Round to the nearest tenth. - $19,16,20,7,9,10,15,7,11$