At a birthday party, the ratio of children to adults is 4:1. If the average time for the three-legged race for adults was 1 minute and 25 seconds, and the average time for the children was 3 minutes and 20 seconds, what is the maximum the average can be for all the guests at the birthday party?

Answer: The maximum the average can be for all the guests at the birthday party is 2 minutes 57 seconds.

Step-by-step explanation:

Since the ratio of adults to children is 4:1, then it follows that:

4/5 of the people are children

1/5 of the people are adults

A weighed average of the times would give:

1 minute 25 seconds = 85 seconds [for 1/5 of the people (the adults) ]

3 minutes 20 seconds = 200 seconds [for 4/5 of the people (the children) ]

(85 x 1/5) + (200 x 4/5) = 177 seconds

Therefore, the maximum the average can be for all the guests at the birthday party is 2 mins 57 secs.