Answer: b) 84
Step-by-step explanation:
Let p be the prior estimate of the required proportion.
As per given , we have
p =0.5 (The probability of getting heads on a fair coin is 0.5)
Significance level :
Critical z-value (using z-value table ) :
Confidence interval width : w= 0.18
Thus , the margin of error :
Formula to find the sample size ( if prior estimate of proportion is known.):-
Substitute the values , we get
Simplify ,
[Round of to the next whole number.]
Hence, the number of times we would have to flip the coin =<u>84</u>
hence, the correct answer is b) 84