continuous variable in frequency distribution

A random sample of 81 students was tested for the problem solving approach skills. The variance of the scores obtained from the sample was found to be 144. Find the 80% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed...

The standard deviation of the hemoglobin values (g/100ml) of 10 children is 1.7. Find the 99% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed. => 1.26 < σ 2 < 14.75 ; 1.12 < σ < 3.84 or 1.1 <..

The average age of media reporters worldwide is 35 years with a standard deviation of 6 years. If a media channel employs 50 media reporters, then what is the probability that their mean age lies between 34 and 37 years? Assume that the variable is normally distributed. => 87.15..

The mean time a student spends on a computer is 4 hours per day. Assume the standard deviation is 0.7 hour. Find the percentage of students who spend more than 4.3 hours on the computer. Assume the variable is normally distributed. => 66.56% or 88.44% or 33.36% or 16.56%..

The average number of hours a vehicle is in the parking lot of the company is 8. Assume the variable is normally distributed and the standard deviation is 2 hours. If 10 vehicles are selected at random, then find the probability that the mean number of hours they are kept in the..

The mean weight of girls in grade 12 of school X is 125 pounds, and the standard deviation is 20 pounds. If a sample of 25 girls is selected, then what is the probability that the mean of the sample will be greater than 128 pounds? Assume the variable is normally distributed. =>..

The average age of the employees in an organization is 34 years. Assume the variable is normally distributed and the standard deviation is 4. If 25 employees are selected at random, then find the probability that the sample mean age of the employees is less than 35 years. => 89...

$ x is distributed equally among 5 children. Which of the following variable expressions represents the share of each child? => 5 + x or x - 5 or x 5 or 5 x..

On the annual day function of a school, chocolates were bought to be distributed among the students of 6, 7, 8 and 9 grades. The frequency table shows the number of chocolates that were distributed among the students of different grades. How many chocolates did the man..

Which among the following statement(s) is/are true about histograms? I. Midpoints are useful in determining class widths and class boundaries. II. Histograms are useful in displaying cumulative frequencies. III. Histograms are used to display categorical data. IV. Histograms are not used ..