tossing a fair coin

May 2010
11
0
Suppose that a fair coin is tossed repeatedly until a head is obtained for the first time.

(a) What is the expected number of tosses that will be required?
(b) What is the expected number of tails that will be obtained before the first head is
obtained?

does anyone know how to do this one????
 

mr fantastic

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Suppose that a fair coin is tossed repeatedly until a head is obtained for the first time.

(a) What is the expected number of tosses that will be required?
(b) What is the expected number of tails that will be obtained before the first head is
obtained?

does anyone know how to do this one????
The answer to (b) is one less than the answer to (a). Review the geometric distribution to get the answer to (a).
 
May 2010
11
0
i found E(x) in (a) to equal 2 and so (b) would equal 1 but i wasnt sure that was correct. is that what you found?