Answer: 
<u>Step-by-step explanation:</u>
The answer you have selected is correct. The answer to this question is 90.
I don't know if I'm right the answer could be 6x
The rectangle is 7 x 4 so the area is 28 sq cm
The triangle has a base of 4 and a height of 3.
The formula is A = 1/2 * b*h
You have 2 triangles so:
2(1/2)*4*3= 12 sq cm
Add together:
28 + 12= 40 sq cm
Α = 1- (95/100) = 1-0.95 = 0.05
p = 1- α/2 = 1- 0.05/2 = 1-0.025 = 0.975
Degrees of freedom, df = Sample size -1 = 11-1 = 10
From t-tables, with cumulative probability pf 0.975 and df of 10,
Critical value = 2.228
