Answer:
Step-by-step explanation:
we know that
The surface area of the square pyramid is equal to the area of the square base plus the area of its four lateral triangular faces
so
where
b is the length side of the square base
h is the height of the triangular face
Remember that
Each lateral triangular face is a triangle 45°-90°-45°
so
we have
so
substitute in the formula
Answer:
38.46%
Step-by-step explanation:
There are no names or marking that can make the calculator look different, so the order is not important. Then we should use a combination to solve this problem.
There are 40 calculators in one shipment, 37 of them good items and 3 of them are defect items. We need to choose 19 good calculators and 1 defect calculator. The number of ways to do that will be:
*
= 37!
= 53017895700
The number of possible ways to choose 20 calculators out of 40 calculators will be:
=
=137846528820
The chance will be: 53017895700/ 137846528820 = 0.3846= 38.46%