Xiaoming does three times as many problems as Xiao Qiang, which means Xiaoming has twice as many problems as Xiao Qiang.

In the past six days, Xiaoming has to catch up with Xiao Qiang's 60 more questions, and on average, he has to do 60÷6= 10 more questions than Xiao Qiang.

So Xiaoming makes 3×( 10÷2)= 15 (pottery) every day on average.

The comprehensive formula is: 3× [60 ÷ 6 ÷ (3-1)] =15 (trace).

A: Xiaoming does 15 questions every day on average.