A random sample of 14 chocolate energy bars of a certain brand​ has, on​ average, 260 calories per​ bar, with a standard deviation of 15 calories. Assume that the distribution of the calorie content is approximately normal. Construct a 90​% confidence interval for σ.

The body temperatures of a group of healthy adults have a bell-shaped distribution with a mean of 98.34°F and a standard deviation of 0.56°F. Using the empirical rule, find each approximate percentage below. a. What is the approximate percentage of healthy adults with body temperatures within 2 standard deviations of the mean, or between 97.22°F and 99.46°F? b. What is the approximate percentage of healthy adults with body temperatures between 97.78°F and 98.90°F? a. Approximately % of healthy adults in this group have body temperatures within 2 standard deviations of the mean, or between 97.22°F and 99.46°F. (Type an integer or a decimal. Do not round.)

Agricultural scientists are testing a new chicken feed to see whether it increases the number of eggs laid. The scientists divided a flock in half and gave half of the chickens the new feed, while the other half were given a regular feed. The eggs laid in a one-year period for a random sample of 10 chickens using the new feed and 10 chickens using the regular feed are recorded. Assume that the population standard deviation of number of eggs laid is 12 eggs per year for both groups and that the number of eggs laid per year is normally distributed. Let the chickens given the new feed be the first sample, and let the chickens given the regular feed be the second sample. The scientists conduct a two-mean hypothesis test at the 0.05 level of significance to test if there is evidence that the new feed increases the number of eggs laid.   (a)  Which answer choice shows the correct null and alternative hypotheses for this test? Select the correct answer below:   H0:μ1=μ2;…

The body temperatures of a group of healthy adults have a bell-shaped distribution with a mean of 98.33°F and a standard deviation of 0.52°F. Using the empirical rule, find each approximate percentage below a. What is the approximate percentage of healthy adults with body temperatures within 3 standard deviations of the mean, or between 96.77F and 99.89°F? b. What is the approximate percentage of healthy adults with body temperatures between 97.29°F and 99.37°F? a. Approximately% of healthy adults in this group have body temperatures within 3 standard deviations of the mean, or between 96.77°F and 99.89°F. (Type an integer or a decimal. Do not round.)

Construct a  90%  confidence interval for the population mean,  μ . Assume the population has a normal distribution. A sample of  15  randomly selected students has a grade point average of  2.81  with a standard deviation of  0.63 .

In a random sample of ten cell​ phones, the mean full retail price was ​$433.00 and the standard deviation was ​$208.00. Assume the population is normally distributed and use the​ t-distribution to find the margin of error and construct a 99​% confidence interval for the population mean μ. Interpret the results.

Assume all populations are normally distributed. A travel analyst claims that the mean price of a round trip flight from New York City to Los Angeles is less than $507. In a random sample of 55 round trip flights from NYC to LA, the mean price is $502. Assume the population standard deviation is $111. At α = 0.05, is there enough evidence to support the travel analyst’s claim?