The mean time taken to learn the basics of a word processor by all students is 2

Question

The mean time taken to learn the basics of a word processor by all students is 200 minutes with a standard deviation of 20 minutes. Using Chebyshev's theorem, find least what percentage of students will learn the basics of this word processor in 140 to 260 minutes: The following sample data give the number of car thefts during the past 12 days that occurred in a city. 6 3 7 11 5 3 8 7 2 6 9 13 Find the mean, median, and mode. A sample of 10 professors were asked how many cups of coffee they drink each day on the average. The following are their responses. 3 8 2 7 9 5 4 2 1 5 Find the range, variance, and standard deviation. In a shipment of 25 microwave ovens, 2 are defective. If two ovens are randomly selected an tested, find the probability that both are defective. (Without replacement)

Explanation / Answer

1)as 120 to 260 lies in 3 std deviation away from mean

hence from Chebyshev's % with in that interval=(1-1/k2)*100 =88.89%

2)

from above mean =6.67

median =(n+1)/2 th value= 6.5 th value =(6+7)/2 =6.5

mode =3 as it appears highest 2 number of times

3) putting data in ascending order

range=min-max=9-1=8

variance=(66.4/9)=7.38

and std deviation =(7.38)1/2 =2.716

4) probabilty that both are defective =(2/25)*(1/24)=0.0033

2 3 3 5 6 6 7 7 8 9 11 13 total T 80 mean=T/12 6.67

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