Lisa has scored 24, 21, and 20 points in her three basketball games so far. How many points does she need to score in her next game so that her average (mean) is 21 points per game?
Explanation
Check

She needs to score AT LEAST 19 points

Step-by-step explanation:

24 + 21 + 20 + 19 = 84

84 ÷ 2 = 21

we know that

the volume of the oblique pyramid with a square base is equal to

V=\frac{1}{3}BhV=

3

1

Bh

where

B is the area of the base

h is the height of the pyramid

In this problem

The area of the base is

B=EF^{2}\ units^{2}B=EF

2

units

2

h=AB\ unitsh=AB units

The two formulas to calculate h are

Applying the Pythagoras Theorem

h^{2}=AC^{2}-CB^{2}h

2

=AC

2

−CB

2

> h=\sqrt{AC^{2}-CB^{2}}h=

AC

2

−CB

2

h^{2}=AD^{2}-DB^{2}h

2

=AD

2

−DB

2

> h=\sqrt{AD^{2}-DB^{2}}h=

AD

2

−DB

2

therefore

the answer is

AB and EF

AC, CB and EF

AD, DB and EF