5 men
paints
5 houses
in
5 days
Correct Way #1
=
1 man
1 house
Reason: One man can paint fewer houses than five men in the same time.
Correct Way #2
25 days
Reason: 1 man needs more time to paint the same number of houses than 5 men.
Wrong Way #1
1 days
Why wrong? This is not simple ratio. i.e. ¹ 5:5:5
Wrong Way #2
Why wrong? Students may divide both number of men and number of days by 5.
(Note) It is not logical for 1 man to paint 5 houses faster than 5 men.
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