normal distribution

The daily water usage (in gallons per person per day) of 10 families of a colony has a variance of 286. Find the 90% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed. => 152 < σ 2 < 774 ; 12 < σ &l..

Which of the following represents a normal (symmetric) distribution curve? I. Graph 1 II. Graph 2 III. Graph 3 => I only or II only or I and II only or II and III only..

The heights of a group of young women aged 16 - 25 years was found to be normally distributed with a mean of 62.4 inches and a standard deviation of 1.5 inches. Find the probability of a woman having a height between 60 inches and 65 inches, using the standard normal t..

For any specific value of the independent variable, the values of the dependent variable y are normally distributed. This is called the __________ assumption. => independence or linearity or equal - variance or normality..

A survey asks 'How much time do you spend in front of the TV in one week? Suppose the responses are normally distributed, the mean is 10 hours and the standard deviation is 2 hours. Suppose there are 50 responses to the survey question. How many would you expect to spend between..

The local authorities in a certain city install 1600 electric lamps in the streets of the city. If the lamps have a mean life rate of 1000 burning hours, with a standard deviation of 150 hours, approximately what number of lamps might be expected to fail in first 750 burning hours? Assume that the ..

Assume that the weights of 3,000 students at a university are normally distributed with mean 150 pounds and a standard deviation of 2.72 pounds. How many samples would you expect to find the mean below 146 pounds? => 7 or 6 or 5 or 8..

The lifetime of an electronic toy is observed as normally distributed curve with a mean of 300 hours and a standard deviation of 180 hours. What is the probability that a randomly selected toy will last for 300 to 480 hours? => 480 or 300 or 0.68 or 0.34..

The full term birth weight of babies in a hospital is normally distributed with a mean of 3.0 kg and a standard deviation of 0.5 kg. If 300 babies were weighed, about how many of them would be expected to weigh between 2.5 to 3.5 kg? => 250 or 200 or 205 or 100..

What is the area under the normal distribution curve to the left of z = 1.56? => 94.06% or 5.94% or 55.94% or 44.96%..