Answer:
A
Step-by-step explanation:
The volume of the triangular prism is

where
h = height
Base = triangle.
In your case,

then

I believe the answer to your question is D
Answer
Answer
The speedometer is likely to show the speed is either 36.0 mph or 44.0 mph.
To prove
Formula

Where error = |Approx value - Exact value |
First case
As given
A speedometer has a percent error of 10%. The actual speed of the car is 40 mph.
Here
Percentage error = 10%
Exact value = 40 mph
error = - (Approx value - Exact value )
= - (Approx value - 40 )
= - Approx value + 40
Put in the formula


Thus
Approx value = 40 - 4
Approx value = 36 mph
Therefore Option (b) is correct .
Second Case
error = (Approx value - Exact value )
= (Approx value - 40 )
= Approx value - 40
Put in the formula


Thus
Approx value = 40 + 4
Approx value = 44 mph
Therefore Option (c) is correct .
The formula states that:
Faces + Vertices - Edges = 2
So 21 + V - 49 = 2 => V = 2+49-21 = 30
Answer A!