Hello you!

i took a because all i did was i just divided 24 by 2 = 12
however, i don't think i am right though : )
there is a reason they added option d which looks like there are something missing in the triangle.

explain your answer.

Ameteorologist is studying the monthly rainfall in a section of the brazilian rainforest. she recorded the monthly rainfall, in inches, for last year. they were: 10.4, 10.3, 11.7, 11.1, 8.0, 4.4, 2.6, 1.8, 2.5, 4.4, 7.3, 9.5 fill in the missing values in the formula. what is the variance?