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Print How Many Men Does it Take to Change a Light Bulb?


How Many Men Does it Take to Change a Light Bulb?

Answer: Nobody knows because it has never happened.

Unfortunately, in a proper test we have to be a little more scientific in our approach to such questions. Given the question…
“In a group of 100 men, 12 could put up a shelf and change a spark plug. How many men could do neither task?”
…how do we go about solving it?

Percentage of People Able to…


First of all we must examine the data given in the chart and the question and decide what is relevant for this particular question and disregard the rest. The first thing to note is that the group size is 100 men which means that percentages and numbers are equivalent which makes things a little easier. From the chart we can see that 64% of men can put up a shelf and 41% of men can change a spark plug. From the question we know that 12% can do both.
Do you remember Venn diagrams from school? They are the charts with overlapping circles that you probably thought could never be any use to man nor beast in real life but you were wrong!
Venn diagrams from school
Here the left circle represents the group of men who can put up a shelf (52+12) and B represents the group who can change a spark plug. The overlap is those who can do both. The outside rectangle represents the universal set of 100 men. From this we can see that there are 52+12+29=93 men who can do one or other task or both. Therefore there are just 100-93=7 men who can do neither. I wonder if they could change a light bulb though?

takehisa 02 Jul 2014

Where are the charts?

sai 13 Aug 2012


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