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(a)The table below show Business statistics I examination marks for a class of one hundred students in Mount Kenya university.
Marks
10-19
20-29
30-39
40-49
50-59
60-69
Number of students
4
8
a
22
48
b
The mean score of the students was 46.5
(i) Show that the values of a and b are 12 and 6 respectively. (5marks)
(ii) Estimate the median for the above sample. (3marks)
(iii) Determine the variance and the standard deviation (4 marks)
(iv) Given that 32% of the students failed the examination, what was the cut off points.
(3 marks)
(v)Estimate the mode for this data. (3marks)
Marks
10-19
20-29
30-39
40-49
50-59
60-69
Number of students
4
8
a
22
48
b
The mean score of the students was 46.5
(i) Show that the values of a and b are 12 and 6 respectively. (5marks)
(ii) Estimate the median for the above sample. (3marks)
(iii) Determine the variance and the standard deviation (4 marks)
(iv) Given that 32% of the students failed the examination, what was the cut off points.
(3 marks)
(v)Estimate the mode for this data. (3marks)
(a)The table below show Business statistics I examination marks for a class of one hundred students in Mount Kenya university.
Marks
10-19
20-29
30-39
40-49
50-59
60-69
Number of students
4
8
a
22
48
b
The mean score of the students was 46.5
(i) Show that the values of a and b are 12 and 6 respectively. (5marks)
Two groups of 100 people each were taken for testing the use of vaccine. 15 persons contracted the disease out of the inoculated persons, while 25 contracted the disease in the other group. Test the efficiency of the vaccine. use X square value (at 5 percent level for one degree of freedom the value of X square - 3.82)
A student has to take seven more courses before she can graduate. If none of the courses are prerequisites to others, how many groups of four courses can she select for the next semester?
two independent experiments are being conducted in which two different types of drying methods, freeze drying and oven drying are compared. 18 fruits are dried using the freeze drying and the drying time is recorded. the same procedure is done with oven drying. the standard deviation for both methods are known to be 30 minutes. Assume that the mean drying time for both methods are the same and the time taken for fruits to dry using freeze drying method and oven drying method are normally distributed. Find the probability that
a) the sample mean for freeze drying is less than the sample mean for oven drying.
b)the difference between both sample means is larger than 2 minutes.
c)the difference between both sample means is less than1 minutes.
A committee of 5 is to be selected from a group of 6 men and 9 women. If the selection is made randomly, what is the probability that the committee consists of 3 men and 2 women?
The time taken to complete a particular type of a job is distributed approximately normally with mean 1.8 and standard deviation of 0. 1hours.Calculate the estimated completion time (to the nearest minute) that should be set so that there is a 90% chance that the job is completed on time.
Suppose that in a certain country the probability that a male is covid-19 positive is 0.2 and that a female is covid-19 positive is 0.15. Also suppose that 50% of the population is female and that a test shows negative for 1% of people who are covid-19 positive and shows positive 0.2% of people who are covid-19 negative. (a) for a female, what is the probability that she is actually covid-19 positive if a test shows positive. (b) if a sample tests positive, what is the probability that it came from a man?
The following table gives the life time is among 400 radio tube of certain make
Find the mean life-time of the radio tubes
Life-time(in hours)
Number of tubes
Less than 300
Less than 400
Less than 500
Less than 600
Less than 700
Less than 800
Less than 900
Less than 1000
Less than 1100
Less than 1200
20
60
116
194
265
324
374
392
400
#339914 on Dec 2023