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
Answer:
About 9.2 units
Step-by-step explanation:
[8-(-1)^2]+[(5-3)^2]
81+4
sqrt(85)
9.2
Brainliest appreciated :)
Well every time it gets rid of a shell it grows 1 1/3 times larger. So so to see how much it grows after the first time you say
1 cm * 1 1/3 = 1 1/3 cm
to get the next one you do the same
1 1/3 cm * 1 1/3 cm = 16/9
It will keep going multiplying by 1 1/3. So so we can say in an equation that the
(initial size) * 1 1/3 *(number of shells) = length
Or 1cm * 1 1/3 * n = L
We we know the final length is 10cm
So 1 1/3 * n = 10cm
n = 7.5shells
so approximately 7 or 8 shells