Exercise - 4.5

Choose the correct or the most suitable answer . The sum of the digits at the th place of all numbers formed with the help of , , , taken all at a time is ( ) ( ) ( ) ( ) . In an examination there are three multiple choice questions and each question has choices . Number of ways in which a student can fail to get all answer correct is ( ) ( ) ( ) ( ) . The number of ways in which the following prize be given to a class of boys first and second in mathematics, first and second in physics, first in chemistry and first in English is ( ) × ( ) × ( ) × ( ) × . . The number of digit numbers all digits of which are odd is ( ) ( ) ( ) ( ) . . In fingers, the number of ways four rings can be worn is · · · · · · · · · ways. ( ) − ( ) ( ) ( ) . If ( n + ) P ( n + ) = ( ( n − ) ) ( n + ) P n , then the value of n are ( ) and ( ) and ( ) and ( ) and . . The product of r consecutive positive integers is divisible by ( ) r ! ( ) ( r − )! ( ) ( r + )! ( ) r r . . The number of five digit telephone numbers having at least one of their digits repeated is ( ) 90000 ( ) 10000 ( ) 30240 ( ) 69760. . If a − a C = a − a C then the value of ’a’ is ( ) ( ) ( ) ( ) . There are points in a plane and of them are collinear. The number of straight lines joining any two points is ( ) ( ) ( ) ( ) . . The number of ways in which a host lady invite people for a party of out of people of whom two do not want to attend the party together is