CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

A man has 7 friends. In how many ways he can invite one or more of them for a tea party.



Your Answer
A

128

Your Answer
B

256

Correct Answer
C

127

Your Answer
D

130


Solution

The correct option is B

127


He can invite his one friend or two friends or three friends ....... Or all of the seven friends

Selecting one friend out of 7 friends =7C1

Selecting 2 friends out of 7 friends = 7C2

.

.

.

.

Selecting all 7 friends = 7C7

Sum of all these cases = 7C1 + 7C2 + .......... + 7C7  ................................(1)

Add and subtract 7C0

 7C0 + 7C1 + 7C2 + .......... + 7C7 - 7C0

Total number of ways = 7C0 + 7C1 + 7C2 + .......... + 7C7 = 27

 case that no friend be invited 7C0  which we need to excluded

Required number of ways =27 - 1 = 127.

flag
 Suggest corrections
thumbs-up
 
0 Upvotes


Similar questions
View More


People also searched for
View More



footer-image