How many 4 digit numbers contain number 2.
a. 3170
b. 3172
c. 3174
d. 3168?
Answers
3168 4 digit numbers contain number 2.
In permutations there is a method for solving problems like these.
If we carefully observe the question, we are required to find the number of 4-digit numbers which include 2!!!
For that we first find number of 4 digit numbers. Then numbers of 4-digit numbers which don't have 2. Then we subtract the second one from first one.
that is
Number of 4-digit numbers with 2=(Number of 4-digit numbers)-(Number of 4-digit numbers without 2).
So again we will be redirected into permutations.
We have condition that repetition is allowed. We have 10 numbers to be filled in 4 places. Since '0' can't be in thousands place, the number of 4-digit numbers will be 9*10*10*10=9000.
To find number of numbers without 2, we have repetition allowed with 9 numbers in 4 places. Since '0' can't be in first place, number of 4-digit numbers without '2' will be 9*9*9*8=5832
So as said earlier the answer will be 9000–5832=3168.
Answer:
Step-by-step explanation: