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Hbc 2121: Introduction To Business Statistics Question Paper
Hbc 2121: Introduction To Business Statistics
Course:Bachelor Of Commerce
Institution: Dedan Kimathi University Of Technology question papers
Exam Year:2013
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DEDAN KIMATHI UNIVERSITY OF TECHNOLOGY
UNIVERSITY EXAMINATIONS 2013/2014
FIRST YEAR SECOND SEMSETER EXAMINATION FOR BACHELOR OF COMMERCE
HBC 2121: INTRODUCTION TO BUSINESS STATISTICS
DATE: 15TH, DECEMBER 2013 TIME: 8.30 AM – 10.30 AM
==============================================================================
Instructions: Answer question ONE and any other TWO questions
QUESTION ONE (30 MARKS)
a) Giving relevant examples differentiate between discrete and continuous statistics as
used in business and economics. (4marks)
b) One of the most important calculations for business or economics is to find the total. To
find the total sales of 200 agents, for example, would multiply 200 by the mode,
median, or mean sales? Give reasons. (2marks)
c) Given the following data calculate the mean absolute deviation and the standard
deviation
X 60 63 66 69 72 75 78
f 4 12 44 64 56 16 4
(10marks)
d) In the summer of 1993, several dozen economic forecasters gave widely varying
predictions of the inflation rate for the next year, as follows:
Inflation rate ( range of forecasts) 2 – 4% 4 – 6% 6 – 8% 8 -10%
Proportion of forecasters .12 .60 .23 .05
a) What is the average forecast? How does it compare to the inflation rate of 3.9% that
actually occurred? (4marks)
b) What is the standard deviation? (4marks)
e) Suppose on every birth the probability of a boy is 52% and a girl is 48% calculate the
probability that a couple would have two boys and one girl in any order. (6marks)
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QUESTION TWO (20MARKS)
a) The table below shows the prices of average person’s physical diet and the basket of goods, Q, the year 2000 and 2005.
Item
Prices 2000
Prices 2005
Quantity 2000
Quantity 2005
Steak Pepper Bread
$2.20 $2.00 $.50
$3.00 $2.00 $.60
50 2 80
40 3 100
Determine the Laspeyres price index, Paasche price index and Fisher’s ideal index. (10marks)
b) “Statistical enquiries mean some sort of investigation by any agency whatsoever wherein relevant information is collected in numbers rather than words”. Briefly explain the stages that are involved in any statistical enquiry. (10 marks)
QUESTION THREE (20MARKS) In a study of how wheat yield depends on fertilizer, the following observation was made on seven different levels: Fertilizer and yield observations
X, fertilizer( kg/acre)
Y, yield (tons/acre)
100 200 300 400 500 600 700
40 50 50 70 65 65 80
i) Graph these points, and roughly fit a line by eye.
ii) Use this line to predict yield Y, if the fertilizer application X is 400 kgs.
iii) Use least squares formulas to predict Y, when X is 800 kgs.
iv) What is the meaning of slope b? (20marks)
QUESTION FOUR (20MARKS)
a) Define the following terms as used in statistics:
i) Confidence intervals
ii) Chi-square
iii) Nonparametric statistics (6marks)
b) Over the past month, the Radex Corporation has produced 200 truckloads of radios, now stored in its warehouse; initially 44% of the radios were defective in the first 128 “bad” truckloads. After tightening up quality control, the company reduced the defective rate to 15% in the remaining 72 “good” truckloads.
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Now suppose you have been appointed the procurement officer for a large department store. Your first job is to make decision on a truckload of radios your store has just received from Radex. You want to know if it’s one of the bad truckloads – because if it is, you want to return it.
i) If the information above is all you have, what is the chance the truckload is bad?
ii) To test the truckload, you draw a radio at random from it. If this sample radio turns out to be defective, what is the chance the truckload is bad? (14marks)
QUESTION FIVE (20MARKS)
a) Giving relevant examples identify the types of errors found in hypothesis testing.
(4marks)
b) To measure the effect of a fitness campaign, a golf club randomly sampled five members before the campaign, and another 5 after. The weight were as follows:
Before: 168, 195, 155, 183, 169 After: 183, 177, 148, 162, 180
i) Calculate a 95% confidence interval for:
a) The mean weight before the campaign.
b) The mean weight after the campaign. (6marks)
c) Agricultural Farm Products is about to analyze the weights of materials received from suppliers, but the analyses are valid only if the weights are normally distributed. The population of materials is known to have a mean weight of 45 grams and a standard deviation of 15 grams. A sample of 500 units was taken, with weights given in the following distribution. Are these Normally distributed? (10marks)
Weight in grams
Number of observations
Less than 10 10 to 19.99 20 to 29.99 30 to 39.99 40 to 49.99 50 to 59.99 60 to 69.99 70 to 79.99 80 to 89.99
9 31 65 97 115 94 49 24 16
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