Question

4. The number of words that can be formed of letters a,
b, c, d taken two or more at a time are
(ay/60
(b) 55
(c) 50
(d) 45
None of these

-​

Answer 1

Answer:

Answer

a,e - vowels - 2 nos

b,c,d,f - constant - 4 nos

Case 1 : 1 vowel is selected

out of 2 vowels, 1 can be selected in

2

C

1

ways =2

out of 4 constants, 2 constants can be selected in

4

C

2

=

2×1

4×3

=6 ways.

All three letters can arrange among themselves in 3! ways

Thus total possibility = 2×6×3!

=2×6×6=72

Case 2 : 2 vowels is selected

2 vowels can be selected in

2

C

2

ways = 1

1 constant can be arranged in 3! ways

Thus,

total possibility = 1×4×3!

=1×4×6=24

Thus total number of arrangements

= 72+24

=96