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Statistics and Probability
The probability of individuals with blood types A, B, AB and O are 0.45, 0.13,
0.06 and 0.36, respectively. A geneticist tested 100 individual blood types and
found that 40 had type A, 18 had type B, 5 had type AB and 37 had type O. Use
goodness of fit test at 5% level of significance to test whether the observed
frequencies closely correspond to the theoretical ones.
0.06 and 0.36, respectively. A geneticist tested 100 individual blood types and
found that 40 had type A, 18 had type B, 5 had type AB and 37 had type O. Use
goodness of fit test at 5% level of significance to test whether the observed
frequencies closely correspond to the theoretical ones.
Statistics and Probability
Plot the following data about demand for an item. Find the moving averages by
taking n = 3. Use these to forecast next two months’ demand.
Month 1 2 3 4 5 6 7 8 9 10 11 12
Demand 46 56 54 43 57 56 67 62 50 56 47 56
taking n = 3. Use these to forecast next two months’ demand.
Month 1 2 3 4 5 6 7 8 9 10 11 12
Demand 46 56 54 43 57 56 67 62 50 56 47 56
Statistics and Probability
Previous studies on some spherical seeds have revealed that their mean diameter
is 10 mm with a standard deviation of 2 mm. We start with 1000 seeds and pass
them through two sieves so that only seeds whose diameter is between 9.5mm and
10.5mm are left. Find out the following:
(i) How many such seeds will we get?
(ii) If we discard only those seeds with diameter less than 6 mm, then how many
will be left?
is 10 mm with a standard deviation of 2 mm. We start with 1000 seeds and pass
them through two sieves so that only seeds whose diameter is between 9.5mm and
10.5mm are left. Find out the following:
(i) How many such seeds will we get?
(ii) If we discard only those seeds with diameter less than 6 mm, then how many
will be left?
Statistics and Probability
True or False? Justify.
The moving average method used in forecasting uses weighted averages.
The moving average method used in forecasting uses weighted averages.
Statistics and Probability
True or False? Justify.
Number of samples chosen by SRSWOR and SRSWR are same if population size
is 6 and sample size is 2.
Number of samples chosen by SRSWOR and SRSWR are same if population size
is 6 and sample size is 2.
Statistics and Probability
True or False? Justify.
If the correlation coefficient is zero, then the relationship between Y and X is
positively linear.
If the correlation coefficient is zero, then the relationship between Y and X is
positively linear.
Statistics and Probability
True or False? Justify.
If the probability of being left-handed is 0.1, the probability that none of the 3
persons selected randomly is left-handed is 0.729.
If the probability of being left-handed is 0.1, the probability that none of the 3
persons selected randomly is left-handed is 0.729.
Statistics and Probability
True or False? Justify.
The area under the curve of a standard normal distribution between − ∞ and 0 is
0.45.
The area under the curve of a standard normal distribution between − ∞ and 0 is
0.45.
Statistics and Probability
2.2 A countrywide estate agency specializes in selling commercial ventures. Their records show that the mean selling time is less than 90 days. Because of recent economic conditions, they believe that the mean selling time is now greater than 90 days. A countrywide survey of 100 businesses sold recently revealed that the mean selling time was 94 days, with a standard deviation of 22 days. At the 0.10 level of significance, has there been an increase in selling time?
2.3 Given the following ordered arrangement of ungrouped data:
114 118 121 124 127 131 134 137
116 119 122 125 127 131 135 137
116 120 123 125 128 133 135 141
116 121 123 126 129 133 135 143
117 121 124 126 129 134 135 147
Arrange the data in a frequency distribution having the following columns:
Class boundaries, frequency, class mark.
Let the boundary values of the first class be: 110 - < 115
2.4 Consider the data below:
x 1 2 3 4 5
y 3 6 10 12 14
2.3 Given the following ordered arrangement of ungrouped data:
114 118 121 124 127 131 134 137
116 119 122 125 127 131 135 137
116 120 123 125 128 133 135 141
116 121 123 126 129 133 135 143
117 121 124 126 129 134 135 147
Arrange the data in a frequency distribution having the following columns:
Class boundaries, frequency, class mark.
Let the boundary values of the first class be: 110 - < 115
2.4 Consider the data below:
x 1 2 3 4 5
y 3 6 10 12 14
Statistics and Probability
Suppose that the 25
even-numbered students among the 50 students available
for the comparison of classroom and online instruction
(Example 9.5) are older, employed students. We hope that
randomization will distribute these students roughly equally
between the classroom and online groups. Use the Simple
Random Sample applet to take 20 samples of size 25 from the
50 students. These 25 students will be the classroom instruction
group. (Be sure to click “Reset” after each sample.) Record the
counts of even-numbered students in each of your 20 samples.
(a) How many older students would you expect to see in the
classroom instruction group?
even-numbered students among the 50 students available
for the comparison of classroom and online instruction
(Example 9.5) are older, employed students. We hope that
randomization will distribute these students roughly equally
between the classroom and online groups. Use the Simple
Random Sample applet to take 20 samples of size 25 from the
50 students. These 25 students will be the classroom instruction
group. (Be sure to click “Reset” after each sample.) Record the
counts of even-numbered students in each of your 20 samples.
(a) How many older students would you expect to see in the
classroom instruction group?
