Grade 10Magical Mathematics[Interesting Approach]
a man has 7 friends in how many ways can he invite one or more of them to a party
a man has 7 friends in how many ways can he invite one or more of them to a party
1 Answer
Arun
Dear Atharv
He can invite one or more friends by inviting 1 friend, or 2 friends or 3 friends, or all the 7 friends.
1 friend can be selected out of 7 in 7C1
2 friends can be selected out of 7 in 7C2
3 friends can be selected out of 7 in 7C3
4 friends can be selected out of 7 in 7C4
5 friends can be selected out of 7 in 7C5
6 friends can be selected out of 7 in 7C6
7 friends can be selected out of 7 in 7C7
Therefore the required number of ways (combinations) = 7C1 + 7C2 +7C3 + …..... + 7C7 = 27 – 1 = 128 – 1 = 127 ways
Regards
Arun (askIITians forum expert)
Other Related Questions on magical mathematics[interesting approach]
Given that (1+5x)⁴ = 1 + Px + Qx² + Rx³ +..... Find the values of P - 2Q + 3R
Given that (1+5x)⁴ = 1 + Px + Qx² + Rx³ +..... Find the values of P - 2Q + 3R
magical mathematics[interesting approach]
Last Activity: 3 Years ago
9 men and 15 boys working 10 hours a day can make 12 pillars in 42 days, in how many days will 12 men and 22 boys working 8 hours a day can make pillars 4 times the previous number?
9 men and 15 boys working 10 hours a day can make 12 pillars in 42 days, in how many days will 12 men and 22 boys working 8 hours a day can make pillars 4 times the previous number?
magical mathematics[interesting approach]
Last Activity: 4 Years ago
In the given figure, PQ is a tangent at a point C to a circle with centre O. If AB is a diameter, find angle PCA + angle BCQ?
In the given figure, PQ is a tangent at a point C to a circle with centre O. If AB is a diameter, find angle PCA + angle BCQ?
magical mathematics[interesting approach]
Last Activity: 4 Years ago
for any two sets A and B (A-B)U(B-A)U (A intersection B)
for any two sets A and B (A-B)U(B-A)U (A intersection B)
magical mathematics[interesting approach]
Last Activity: 4 Years ago
If someone has got 150 out of 200 marks in term 1 exam and 160 out of 200 marks in term 2 exam then what is the percentage in 30:70
If someone has got 150 out of 200 marks in term 1 exam and 160 out of 200 marks in term 2 exam then what is the percentage in 30:70
magical mathematics[interesting approach]
Last Activity: 4 Years ago