Question

(need answer asap) The histogram shows the time (secs) it took members at a swimming club to

Answer 1

Estimate that the range of 10-20 seconds is 2x taller but 2x thinner than 20-30 seconds.

So, the range from 10-20 is equal to 20-30 (just an estimate)
And we also can estimate 20-30 is equal to 30-40 (as we can't know how much thinner it is.)

From 40-50, it is 2x shorter than 30-40, so we can also estimate that it is 2x less than 30-40. (and 50-60 equal 40-50)

From 70-80 and 80-90, let's say it's 4/5 40-50 and 50-60

So, taking 10-20 as the fixed amount, the total fraction is 1 + 1 + 1 + 1/2 + 1/2 + 4/5 + 4/5 = 28/5.

40-42 is 2/5 40-45.

So, estimate that the fraction of members who took longer than 42 seconds is 28/5 - 1 - 1 - 1 - 2/5 = 11/5.