Answer: C) 133
Step-by-step explanation:
The formula to find the sample size is given by :-

, where z* = Critical z-value
= Population standard deviation for prior study.
E= Margin of error.
As per given , we have
E= 5
The critical z-value for 90% confidence level is 1.645.
Substitute al;l the value sin the above formula , we get




Hence, the minimum sample size needed is 133.
Thus , the correct answer is : C) 133
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Answer:
Therefore the value of 'y' is,

Step-by-step explanation:
Given:

To Find:
y= ?
Solution:
........Given
Step 1. Adding 50 to both the side we get

Step 2. Dividing by 10 on both the side we get

Therefore the value of 'y' is,

To find h, divide the area by the base:
h = 2442 / 12 = 203.5 km.