Homework SourseHow many ways can a person toss a coin 10 times so that the
How many ways can a person toss a coin 10 times so that the number of tails is between 4 and 7 inclusive?
How many ways can a person toss a coin 10 times so that the number of tails is between 4 and 7 inclusive?
Solution
No of tosses = 10 times
Let X be the no of tails then x has p = 0.5
no of tails =4,5,6,7
NO of ways for 4 tails = 10C4
no of ways for 5 tails = 10C5
....
Hence no of ways for 4 to 7 tails = 10C4+10C5+10C6+10C7
= 210+252+210+120+45+10+1
= 848
