A group of 10 students working one hour day complete a job in 12 days. In how rm days will 12 students in group working (hour per day finish the same job?

A) 9 days

B) 8 days

C) 11 days

D) 10 days

10 students can finish work = 12 days 

1 student can finish work= 10 x 12 = 120 days

12 student will finish work= 120/12 = 10 days