The table gives information about the times taken, in minutes, by 22 students to cycle a race.
Time (t minutes) Frequency
15 4
20 1
25 7
30 10
Work out an estimate for the mean time.
Give your answer in minutes and correct to 3 significant figures.
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Which of the following is an example of an opposing signal? no examplthates given.   i would say, that traffic lights in a city at major intersections direct the flow of traffic in opposite directions so would be an example.also, stop signs on either side of the same street would be an example. at a train crossing, the light for allowing car traffic in opposite directions or not would be another example.