Yvonne swims 10 laps in 5 minutes and her younger sister swims half as many laps in 5 minutes so she swims 10/2 = <<10/2=5>>5 laps in 5 minutes
Joel can swim 3 times the amount of his youngest sister’s 5 laps so he can swim 3*5 = <<3*5=15>>15 laps in 5 minutes
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