A coin is tossed 40 times. A person, who claims to have extrasensory perception, is asked to predict the outcome of each flip in advance. She predicts correctly on 26 tosses. what is the probability of being correct 26 or more times by guessing? Does this probability seem to verity her claim?
A) 0.0418, yes
B) 0.0409, yes
C) 0.0418, no
D) 0.0409, no
A) 0.0418, yes
B) 0.0409, yes
C) 0.0418, no
D) 0.0409, no
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this can be easily solved using the binomdist, but the ans of 0.0403 suggests that you are expected to use the normal approximation.
the q should then SAY so !
a. µ = np = 40*0.5
b. σ = sqrt(npq) = sqrt(40*0.5.*0.5.)
c. with continuity correction, 26 or more becomes 25.5 or more
d. z = (25.5-µ)/σ
e. P(x ≥ 25.5 ) = P(z ≥ (25.5-µ)/σ) = 0.0409, no <------
the q should then SAY so !
a. µ = np = 40*0.5
b. σ = sqrt(npq) = sqrt(40*0.5.*0.5.)
c. with continuity correction, 26 or more becomes 25.5 or more
d. z = (25.5-µ)/σ
e. P(x ≥ 25.5 ) = P(z ≥ (25.5-µ)/σ) = 0.0409, no <------