tn=a+(n−1)d Here, tn= last term a= first term n=n. of terms d= common difference P(A)=n(A)∕n(S) P(A) is the probability of an event "A" n(A) is the number of favorable outcomes. n(S) is the total number of events in the sample space.
130=40+(n−1)⋅1 ⇒130=40+n−1 ⇒n=91 Now, LCM of 2,3,4=12 So, numbers which are divisible by 12 between 40 to 130=48,60,72,84,96, 108,120 So, total of 7 numbers are there So, Probability =7∕91 ∴ The required probability is 7∕91.