A survey is planned to estimate the proportion of voters who support a proposed gun control law. The estimate should be within a margin of error of ±5% with 90% confidence, and we do not have any prior knowledge about the proportion who might support the law. How many people need to be included in the sample?

Round your answer up to the nearest integer.

sample size = _____

Answer:

The sample size is $n = 271$

Step-by-step explanation:

From the question we are told that

The margin of error is E = 5% = 0.05

Generally given that there was no prior knowledge about the proportion of who might support the law, we will assume the sample proportion to be

$\^ p = 0.5$

From the question we are told the confidence level is 90% , hence the level of significance is

$\alpha = (100 - 90 ) \%$

=> $\alpha = 0.05$

Generally from the normal distribution table the critical value of $\frac{\alpha }{2}$ is

$Z_{\frac{\alpha }{2} } = 1.645$

Generally the sample size is mathematically represented as

$n = [\frac{Z_{\frac{\alpha }{2} }}{E} ]^2 * \^ p (1 - \^ p )$

=> $n = [\frac{1.645 }{0.05} ]^2 * 0.5 (1 - 0.5 )$

=> $n = 271$

5 0

2 years ago

PLS HELP TIMED QUESTION!!!

ser-zykov [4K]

Answer:

About 5043.58

Step-by-step explanation:

The standard form for an exponential decay after t time is:

$\displaystyle f(t)=a(r)^{t/d}$

Where a is the initial value, r is the rate decay, t is the time that has passed, and d is the amount of time it takes for 1 cycle.

The initial value is 9800. So a = 9800.

The quantity cuts in half. So, r = 1/2.

And it cuts in half every 6 days. For this question, we will convert this to hours. 6 days = 144 hours. So, we can let d = 144, where t will be in hours.

Therefore, our function is:

$\displaystyle f(t)=9800\Big(\frac{1}{2}\Big)^{t/144}$

Where t is the amount of time that has passed, in hours.

Then the quantity left after 138 hours will be:

$\displaystyle f(138)=9800\Big(\frac{1}{2}\Big)^{138/144}\approx 5043.58$

7 0

2 years ago