Question

in a given year, the rate of flu infection for the general public was 8.3%. And sample of 200 people who receive the flu vaccine, the rate of flu infection was just 3.5%. What conclusion should you draw?​

Answer 1

Answer:

$\fbox{\begin{minipage}{10em}Option A is correct\end{minipage}}$

Step-by-step explanation:

Step 1: Define significance level

In this hypothesis testing problem, significance levels α is selected: $0.05$, the associated z-value from Laplace table:

Φ($z$) = α - $0.5 = 0.05 - 0.5 = -0.45$

=> $z$ = $-1.645$

Step 2: Define null hypothesis ($H_{0}$) and alternative hypothesis ($H_{1}$)

$H_{0}$ : rate of flu infection $p$ = 8.3% or 8.3/100 = 0.083

$H_{1}$ : rate of flu infection $p$ < 8.3% or 8.3/100 = 0.083

Step 3: Apply the formula to check test statistic:

$K = \frac{f - p}{\sqrt{p(1 - p)} } * \sqrt{n}$

with $f$ is actual sampling percent, $p$ is rate of flu infection of $H_{0}$, $n$ is number of samples.

The null hypothesis will be rejected if $K < z$

Step 4: Calculate the value of K and compare with $z$

$K = \frac{(\frac{3.5}{100}) - 0.083}{\sqrt{0.083(1 - 0.083)} } * \sqrt{200} = -2.46$  

We have $-2.46 < -1.645$

=>This is good evidence to reject null hypothesis.

=> The actual rate is lower. (As $H_{1}$ states)

Hope this helps!

:)