Answer:
They now should survey 800 people.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of , we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
The margin of error is:
In this problem:
Same level of confidence, so same z
Same proportion, so same
We have to change n
We want to reduce the margin of error by half.
M is inverse proportion to the square root of n. That is, as n increases, M decreases.
We want to decrese M by half. So we need to increase n by a factor of 2^2 = 4
The first survey had a sample of 200 people
Increasing by a factor of 4.
200*4 = 800
They now should survey 800 people.
Answer:
1.5 or 1 1/2 same thing basically
Step-by-step explanation:
Answer:
75
120
Step-by-step explanation:
Let the first mechanic's hourly rate = x
Let the second mechanic's hourly rate = y
x + y = 195
15x + 5y = 1725 Divide this equation by 5
3x + y = 345 Write the first equation below this one. Subtract
<u>x + y = 195</u>
2x = 150 Divide by 2
x = 150/2
x = 75
====================
x + y = 195
75 + y = 195
y = 195 - 75
y = 120
Answer:
awww well look at that my best friend is on brainly, i need help too <3
Step-by-step explanation: