Answer:
315 times
Explanation:
We know that the friend can clap his hands 28 times in 12 seconds. First, we need to know how many times can he clap his hands in 1 second:
To do it we have to divide the times he can clap his hands by the time in seconds:
28/12 = 2.333333
He can clap his hands 2.333333 times in 1 second:
Now we want to know how many times will he clap his hands in 2.25 minutes
We have to change 2.25 minutes into seconds:
1 (minute) = 60 (seconds in 1 minute)
2.25 (minutes) * 60 (seconds in 1 minute) = 135 seconds
After we get the seconds he is going to clap his hands, we have to multiply the times he claps times the seconds:
2.3333333 times * 135 seconds = 315
315 times in 2.25 minutes