Practise Tests
31
There are 11 alphabets A, H, I, M, O, T, U, V, W, X, Y. They are called symmetrical alphabets. The remaining alphabets are known as asymmetrical alphabets. How many three-lettered words can be formed such that at least one symmetrical letter is there?
Answer : Option D
Explanation:
There are 11 symmetrical alphabets A, H, I, M, O, T, U, V, W, X, Y and number of asymmetrical letters will be 15
Total number possible of words = 26 × 26 × 26 = 17576
Number of words without any symmetrical letters = 15 × 15 × 15 = 3375
Number of words with at least one symmetrical letter
= 17576 − 3375 = 14201
Hence, option 4.
32
How many 4 digit numbers contain a digit 2?
Answer : Option D
Explanation:
First all the four digit numbers using digits 0 to 9
__9__ x _10__ x _10_ x _10_ = 9000 numbers
Second all the four digit numbers using digits 0 to 9 which do not contain digit 2
__8__ x _9__ x _9_ x _9_ = 5832 numbers
Now Subtract
9000 - 5832 = 3168
