Question

A number of two digits is formed using the digits 1, 2, 3, . . .,9. What is the probability that the number so chosen is even and less than 60?

Answer 1

The last step is by using fundanental principle

Answer 2

Answer:

Probability = 20/81  ( uf repetition of digits allowed)

Probability = 1/4 ( if repetition of digits not allowed)

Step-by-step explanation:

two digits number using 1 , 2 , 3 , ..........................9

Would be  9 * 9  = 81   ( if repetition of digits allowed)

total 2 digit numbers formed = 81

even and less than 60

=> 1 st digit can be 1 , 2 , 3 , 4  or 5

& 2nd digit can be  2 , 4 , 6 , 8

So such numbers = 5 * 4 = 20

Probability = 20/81

( if repetition of digits not allowed)

then total numbers = 9 * 8 = 72

even and less than 60 = 20 - 2 = 18   ( as 22 & 44 will not be there)

Probability = 18/72 = 1/4