wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

How many 3-digit numbers can be formed from the digits 5, 6, 7, 8 and 9 assuming that

(i) Repetition of the digits is allowed?

(ii) Repetition of the digits is not allowed?


A
27 and 6
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
15 and 12
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
125 and 60
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
60 and 15
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C 125 and 60

(i) Let the 3-digit number be ABC, where C is at the units place, B at the tens place and A at the hundreds place.

Now when repetition is allowed,

The number of digits possible at C is 5. As repetition is allowed, the number of digits possible at B and A is also 5 at each.

Hence, the total number possible 3-digit numbers =5 × 5 × 5 =125

(ii) Let the 3-digit number be ABC, where C is at the units place, B at the tens place and A at the hundreds place.

Now when repetition is not allowed,

The number of digits possible at C is 5. Let’s suppose one of 5 digits occupies place C, now as the repletion is not allowed, the possible digits for place B are 4 and similarly there are only 3 possible digits for place A.

Therefore, The total number of possible 3-digit numbers=5 × 4 × 3=60


flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
"Number of ways of Arranging ""n"" things taken ""k"" at a time, With and Without Repetition "
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon