On a test, the marks for ten students are: 2 students, 85%; 4 students, 78%; 3 students, 66%; and 1 student, 92%. What is the average mark on the test? (Exact
Answer)

77.2%

Step-by-step explanation:

The average formula is:

Let's first find the sum of all the numbers (remember sum means to add):

(2)(85) + (4)(78) + (3)(66) + 92 = ?

170 + 312 + 198 + 92 = 772

There are marks for 10 students so that is what goes at the bottom (10 students, 10 test scores)

Plug both things into the equation:

Therefore, the average mark on the test was 77.2%

Hope this helps!!

- Kay :)

d. bc = 12 and ef = 16

step-by-step explanation:

we are given that δabc : δdef such that .

also, it is given that

so, from the options, we need that .

a.

b.

c.  

d.

as, we can see that only option d gives the same ratio as i.e. .

hence, the possible lengths are bc = 12 and ef = 16.