Re: In a survey, 86 high school students were randomly selected
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12 Nov 2023, 09:20
Here is how I solved it:
First compute the median, since that is the easiest. Since there are 86 values, the median will be the average of the 43rd and 44th value, which is contained in the set "6-10". Therefore, the median can be at least 6 and at most 10.
Now compute the minimum of the mean - by taking the lowest of each set.
The calculation is as follows: (1*14)+(35*6)+(16*11)+(16*5)+(5*21)+(4*26)+(7*31)=906
89 times 10 is 890, so if the sum is 906 - then that implies that the average is at least 10.something, which is greater than the highest value of our median (10).
Note that the above method is not great - you have to estimate the the number of people, and it is likely not very precise (for example you could estimate a value wrong and get something like 890). It is far better to remember how median and mean are affected by distribution, which would lead you to the correct solution in 20 seconds.