Question

If E = {1,2,3,4}, F = {1,2}, then number of onto functions from E to F is

• A. 14
• B. 16
• C. 12
• D. 8

Answer 1

Answer: (A)

14

Answer 2

Total number of function = 2⁴ ($\because$there are 2 elements of codomain and 4 elements in domain)

Note that onto functions are those whose codomain = Range.

Here in two cases function will be not onto.

(i) When all elements of set E corresponds to “1” of F.

(ii) When all elements of set E corresponds to “2” of set F

∴ Number of onto function = 16 – 2 = 14