Ateacher is experimenting with a new computer-based instruction and conducts a study to test its effectiveness. in which situation could the teacher use the two-sample t-test for comparing two population means?

From a normally distributed population,  if two samples of size less than 30 taken out , then we use t-test to test the difference between the population means.

The conditions which are necessary to use a t-test are :-

1. Each population must have normal distribution.

2. Both the samples must be independent.

Now, if a teacher is experimenting with a new computer-based instruction and conducts a study to test its effectiveness, then to use a t-test all the above conditions are necessary.

step-by-step explanation:

a.   since the profit made in 2012 is equal to the profit made in 2014, the profit is           symmetric about the line y = 120,000.

step-by-step explanation:

given that megan owns a clothing boutique.

the profits of 2010, 11, are recorded and shown as follows:

years since     2010 0     1     2     3       4       5

profits made in 1000's   39       84     111     120   111     84

we find that profit gradually increases form 2010 to 2013 upto 120,   then starts decreasing.

the profits for 2012 and 2014 are the same while that of 2011 and 2015 are also the same.

this shows that there is symmetry about the line profit = 120000

hence answer is:

a.   since the profit made in 2012 is equal to the profit made in 2014, the profit is           symmetric about the line y = 120,000.

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i believe that the answer is

b. y-1=-2(x-4)

hope this !