Statistics and Probability Answers

The burning time of a rocket (measured in seconds) can be thought of as a random variable having uniform distribution on the interval (0,b). 10 rockets yielded the following burning times: 8.7,10.9,7,12,11,7,9.10. Then find an unbiased estimate of b. 

Select one: a.9 b.18 c.12 d.15 

If two independent samples of sizes m=26 and n=8 are taken from normal population, what is the probability that the variance of the first sample will be at least as large as the variance of the second sample?

Select one:a. 0.05b. 0.10 c.0.20 d. 0.01

The standard deviation of a population is 2.50 cms. What is the probability that in a random sample of size 100 the sample mean will differ from the population mean by 0.75 or more?

Select one: a. 0.9974 b. 0.0013 c. 0.9987 d. 0.0026 

Let p be the probability that a coin will fall head in a single toss in order to test Ho : p = 1/2 against H1 : p = 3/4 . The coin is tossed 5 time and Ho is rejected if more than 3 heads obtained. Find the probability of type II error.

Select one: a. 3/8  b. 47/128  c. 9/64  d. 11/24 

The mean weight of luggage checked by a randomly selected economic class passenger flying between two cities on a certain airline is 40Ib, and the standard deviation is 10 lb. The mean and standard deviation for a business class passenger are 30lb and 6 lb respectively. If there are 50 economic class and 12 business class passengers on the flight, what is the variance of total luggage weight?

Select one:  a. 2360  b. 5000  c. 432  d. 5432 

How many different samples of size n=3 can be obtained from a finite population of size N=9 . 

Select one: a. 42 b. 84 c. 21 d.7 

The probability that the sample man should not differ by population mean by more than a/2 units is 0.95, where σ is the population standard deviation. For the validity of the statement, what should be the size of the sample?

Select one:

a. 18

b. 16

c. 12

d. 20

A basket contains 10 balls of which z are green and the remaining are red. To test H: 1 = 4 versus H, :1=6, three balls are selected at random without replacement and He rejected if all the three balls are green. Find the probability of committing type II error.

Select one:

a 2/3

b.5/6

c. 1/3

d. 3/4

From 4 red, 5 green, and 6 yellow apples, how many selections of 9 apples are possible if 3 of each color are to be selected?