Answer:
We conclude that the mean contents of cola bottles is more than or equal to the advertised 300 ml.
Step-by-step explanation:
We are given that Bottles of a popular cola drink are supposed to contain 300 ml of cola. The distribution of the contents is normal with standard deviation of 3 ml.
A student who suspects that the bottler is under-filling measures the contents of six bottles. The results are: 299.4, 297.7, 301.0, 298.9, 300.2, 297.0
<u><em>Let </em></u>
<u><em> = mean contents of cola bottles.</em></u>
SO, Null Hypothesis, 
: 
300 ml {means that the mean contents of cola bottles is more than or equal to the advertised 300 ml}
Alternate Hypothesis, 
: < 300 ml {means that the mean contents of cola bottles is less than the advertised 300 ml}
The test statistics that will be used here is <u>One-sample z test statistics</u> as we know about the population standard deviation;
T.S. = 
~ N(0,1)
where, 
= sample mean contents of cola bottle = 
= 299.03 ml
= population standard deviation = 3 ml
n = sample of bottles = 6
So, <em><u>test statistics</u></em> = 
= -0.792
<em>Now at 5% significance level, the z table gives critical value of -1.6449 for left-tailed test. Since our test statistics is more than the critical value of z as -0.792 > -1.6449, so we have insufficient evidence to reject our null hypothesis as it will not fall in the rejection region due to which we fail to reject our null hypothesis.</em>
Therefore, we conclude that the mean contents of cola bottles is more than or equal to the advertised 300 ml.
