standard deviation formula

The scores made by candidates in a certain test are normally distributed with mean 500 and standard deviation 100. What percentage of candidates received scores greater than 700? => 2.28% or 2.82% or 47.72% or 47.27%..

The scores made by candidates in a certain test are normally distributed with mean of 500 and standard deviation of 100. What percentage of candidates received scores between 400 and 700? => 88.15% or 81.85% or 88.51% or 85.81%..

In an aptitude test conducted to qualify for a job, the scores given were normally distributed with a mean of 75 and a standard deviation 8. If only top 15% were to be selected, then find the cut - off scores. => 83.8 or 88.3 or 83.3 or 85..

A machine produces bolts, of which 10% are defective. Find the probability that in a random sample of 400 bolts produced by the machine, between 35 and 45 will be defective. Assume a standard deviation of 6. => 0.5640 or 0.6405 or 0.4605 or 0.4560..

The average price of a bicycle is $300. The prices of the bicycles are normally distributed with a standard deviation of $60. What is the probability that a randomly selected bicycle costs more than $450? => 0.62% or 6.2% or 3.8% or 0.38%..

The number of stamps of different countries collected by Edward are 96, 98, 98, 105, 36, 87, 95 and 93. Find the mean and the standard deviation. => 416.25, 20.4 or 88.5, 20.4 or 20.4, 5.77 or 20.4, 4.51..

In a report, the standard deviation of the weights of male student athletes is stated as 2 pounds. The standard deviation of weight of a random sample of 24 male student athletes was found as 1.9 pounds. Find the chi-square test value. At α = 0.01 is th..

A retail garment shop receives a shipment of trousers, with a standard length of 49.0 in. and a standard deviation of 1.0 inch. A random sample of 32 trousers had a mean length of 48.8 in. Find the standard error. => 5.0 or 3.2 or 1.0 or 0.18..

In a survey conducted, 4 out of every 7 people play computer games. If 147 people are selected at random, then find the standard deviation of the number of people playing computer games. => 36 or 63 or 6 or 84..

Which of the following controls the spread of normal curve? I. standard deviation II. mean III. median IV. mode => III and IV only or II only or III only or I only..