Abhishek Jain typed 50 pages at the rate of 30 pages per hour on Sunday. On Monday, he could only type 50 extra pages at the rate of 20 pages per hour. What has his average rate of typing been ...
To evaluate the statement "The total number of all possible samples of size 3 without replacement from a population of size 7 is 21," we need to use the concept of combinations. Combination Formula The number of ways to choose a sample of size \(r\) from a population of size \(n\) without replacemenRead more
To evaluate the statement “The total number of all possible samples of size 3 without replacement from a population of size 7 is 21,” we need to use the concept of combinations.
Combination Formula
The number of ways to choose a sample of size \(r\) from a population of size \(n\) without replacement is given by the combination formula:
\[
C(n, r) = \frac{n!}{r!(n-r)!}
\]
where \(n!\) denotes the factorial of \(n\).
Application to the Statement
In this case, we have a population size \(n = 7\) and a sample size \(r = 3\). Plugging these values into the combination formula:
\[
C(7, 3) = \frac{7!}{3!(7-3)!} = \frac{7!}{3! \times 4!} = \frac{7 \times 6 \times 5}{3 \times 2 \times 1} = 35
\]
Conclusion
The statement “The total number of all possible samples of size 3 without replacement from a population of size 7 is 21” is false. The correct number of samples is 35.
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To find Abhishek Jain's average typing rate overall, we can use the formula: \[ \text{Average Rate} = \frac{\text{Total Pages Typed}}{\text{Total Time Spent Typing}} \] On Sunday, he typed 50 pages at the rate of 30 pages per hour. So, the time spent typing on Sunday is: \[ \text{Time on Sunday} = \Read more
To find Abhishek Jain’s average typing rate overall, we can use the formula:
\[
\text{Average Rate} = \frac{\text{Total Pages Typed}}{\text{Total Time Spent Typing}}
\]
On Sunday, he typed 50 pages at the rate of 30 pages per hour. So, the time spent typing on Sunday is:
\[
\text{Time on Sunday} = \frac{\text{Pages Typed}}{\text{Rate}} = \frac{50}{30} \text{ hours}
\]
On Monday, he typed 50 extra pages at the rate of 20 pages per hour. So, the time spent typing on Monday is:
\[
\text{Time on Monday} = \frac{\text{Pages Typed}}{\text{Rate}} = \frac{50}{20} \text{ hours}
\]
The total pages typed over both days is:
\[
\text{Total Pages Typed} = 50 + 50 = 100 \text{ pages}
\]
The total time spent typing is:
\[
\text{Total Time Spent Typing} = \text{Time on Sunday} + \text{Time on Monday} = \frac{50}{30} + \frac{50}{20} \text{ hours}
\]
Now, we can calculate the average rate:
\[
\text{Average Rate} = \frac{\text{Total Pages Typed}}{\text{Total Time Spent Typing}} = \frac{100}{\frac{50}{30} + \frac{50}{20}} \text{ pages per hour}
\]
\[
\text{Average Rate} = \frac{100}{\frac{5}{3} + \frac{5}{2}} = \frac{100}{\frac{10}{6} + \frac{15}{6}} = \frac{100}{\frac{25}{6}} = \frac{100 \times 6}{25} = \frac{600}{25} = 24 \text{ pages per hour}
\]
So, Abhishek Jain’s average typing rate overall is 24 pages per hour.
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