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Suppose that a random sample of 25 mining caps was tested from a population of 3000 mining caps and 20 exploded properly. Give the lower limit of a 80% confidence interval for the proportion of mining caps that will explode properly.
If a random sample of 50 cups of soda dispensed from a machine showed the mean amount of soda dispensed was 7.9 ounces with s=0.35 ounces, find the confidence level if the margin of error is 0.11904?
the length of 5000 corn cobs produced from a local wholesaler are measured and recorded. the lengths X, are found to be normally distributed with a mean of 9cm and a variance of 0.25cm². Find the probability that a corn cob selected at random from the wholesaler has a length between 8.5cm and 9.25cm.
Experience has shown that the time taken to drive from city A to city B is normally distributed, with an average time (µ) of 65 minutes, and a standard deviation (σ) of 11 minutes. A sample of 88 driving trips between the two cities is randomly selected. Determine the standard error for this sample.
If you want to carry out a statistical test at α = 0.01. to test whether the population mean is equal to 500 or not, using a sample size of 300, with a test statistic of z = 1.97, your conclusion should be_____.
Select one:
a. do not reject the null hypothesis
b. reject the null hypothesis
c. only reject when the test statistic is negative
d. not enough information to determine
1.Light bulbs having a mean life of 2400 hours and a standard deviation of 62 hours are used for a consignment of 4200 bulbs.
a.) Determine the number of bulbs likely to have a life in excess of 2500 hours.
b.) Determine the percentage of bulbs with life in between 2200 hours and 2500 hours.
c.) Determine the percentage of bulbs with life in between 2400 hours and 2600 hours
Consider the letters from the word ACCOUNT. How many ways can 3 letter words be formed without using the letter C and end with the letter A, if repetition is not allowed.
The following data give the weekly wages of the workers in a firm their total working hours and the mean working hour per workers.
Calculate the mean weekly wage per works.
Wage group (br)
total hour worked
Mean number of hours worked per workers
800-1000
168
12
1000-1200
170
10
1200-1400
225
3
1400-1600
272
8.5
1600-1800
126
7
1800-2000
91
6.5
Give the following frequency distribution with some missing frequencies
Class
10-20
20-30
30-40
40-50
50-60
60-70
70-80
Frequency
185
f2
34
180
136
f6
50
If the total frequency is 686 and the midian is 42.6 Find out the missing frequencies f2 and f6.
