Q40
How many four-lettered passwords can be formed by using symmetrical letters only? (repetitions not allowed)
Answer: C
4 out of the 11 symmetrical alphabets need to be selected,
Also the order of alphabets needs to be accounted for (as it is a password)
∴ 11P4 = = 11 × 10 × 9 × 8 = 720 × 11 = 7920
Hence, option (c).