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A medical researcher wishes to see whether the variance of the heart beats (in beats per minute) of smokers is different from the variance of heart rates of people who do not smoke. Two samples are selected and the data shows that 26 smokers have a variance of 36 in their heart beats and 18 non smokers have a variance of 10. using a=0.05, is there enough evidence to support the claim that the variances are equal? Assume the variable is normally distributed
(a) Construct a 95% confidence interval estimate for the population mean weight of apples.
(2 marks)
(b) The researcher suggests doing the study again so that 98% confidence interval estimate for the population mean weight of apples is (5.8835,6.1165) kg. How large should the sample size be?
(3 marks)
(a) What is the probability that the salary of an employee is higher than $18000? (3 marks)
(b) There is 80% chance that the salary of an employee is less than $t. Find the value of t.
Construct a 90% confidence interval for the mean fill weight.
Use the value 3.14 for π . Round your answer to the nearest hundredth.
The average life of certain type of small motors is 10 years with standard deviation of 2 years. Suppose that the life of motors is normally distributed. Then what percentage of motors will
i) Between 8 and 12
ii) Between 6 and 8
between 10 and 12
between 8 and 10
between 12 and 14
Question No. 1 (4 Marks)
A car wholesaler estimates the quantity of new cars retailed that have been returned back a many number of times for the rectification of defects during the warranty. The results are given in the following table. Show complete working.
Number of cars
returns back
0 1 2 3 4
Probability 0.25 0.34 0.22 0.07 0.03
a. Compute the mean of the number of cars returns for rectifications for defects during the warranty time.
b. Calculate the variance of the number of cars returns for rectifications for defects during the warranty time.
(a)Construct a 95% confidence interval estimate for the population mean weight of apples.
(2 marks)
(b)The researcher suggests doing the study again so that 98% confidence interval estimate for the population mean weight of apples is (5.8835,6.1165) kg. How large should the sample size be?
(3 marks)
#340153 on Dec 2023