A reaction is first order in A and second order in B
How is the rate affected on increasing the concentration of B three times ?

Explanation

Rate `= k [A] [B]^(2) `
If concentration of [B] is increased three times, then
Rate `= k [A] = [3B] = 9k [A] [B] ^(2)`
So, rate increases by nine times when [B] becomes fripled.