Please help, binomial probability question (1 Viewer)

[matt161989]

Hi, this question is probably easy and i just don't get it. The question is:
"If ten coins are tossed 50 times, in how many cases would we expect the number of heads to exceed the number of tails?" (It's q25 in exercise 29(b) of the fitzpatrick 3 unit book)

I work it out as if there's 50 events, i.e coin tosses, and work out the probability of rolling 26 heads then 27 heads and 28 heads and so on until 50 heads, i then add these up, and get 0.44386..., i multiply this by 50 and get 22, but the answer in the book is 19, what am i doing wrong?

Please help if you have time, thanks in advance

 

[jake2.0]

Hi, this question is probably easy and i just don't get it. The question is:
"If ten coins are tossed 50 times, in how many cases would we expect the number of heads to exceed the number of tails?" (It's q25 in exercise 29(b) of the fitzpatrick 3 unit book)

I work it out as if there's 50 events, i.e coin tosses, and work out the probability of rolling 26 heads then 27 heads and 28 heads and so on until 50 heads, i then add these up, and get 0.44386..., i multiply this by 50 and get 22, but the answer in the book is 19, what am i doing wrong?

Please help if you have time, thanks in advance

Work out the Pr of 6 or more heads in 10 coin tosses and then multiply that by 50.
so =[(10C6 + 10C7 + 10C8 + 10C9 + 10C10)*(.5^10)]*50 = 18.84 = 19

 

[matt161989]

thanks very much

 

[jake2.0]

No worries