Page 160 - Math Course 2 (Book 2)

Understanding Weighted Averages

Percents

A recipe calls for mixed nuts with 50% peanuts. Let’s Begin
1
pound of 15% peanuts has already been used.
2
How many pounds of 75% peanuts needs to be add
to obtain the required 50% mix?
Speed of One Vehicle
1
A.
2 Examples
B. 18
25
1
C.
4 AIR TRAVEL
7 Mirasol took a non-stop flight to visit her grand-
D.
10 mother. The 750-mile trip took three hours and 45
minutes. Because of bad weather, the return trip
took four hours and 45 minutes. What was her
Answer average speed for the round trip?

To find the average speed for each leg of the trip,

rewrite d= rt as r = d
t
Going
MO. 11 - L3b d 750 miles
r = = or 200 miles per hour
t
3.75 hours
Solving Uniform Motion Returning
Problems r = = 750 miles
d
or 157.9 miles per hour
t
4.75 hours
Round trip
Vocabulary A-Z 200(3.75) + 157.9(4.75)

Let us learn some vocabulary M = 3.75 + 4.75 Definition of
weighted average
1500
= or 176.5 Simplify.
uniform motion problem 8.5
Uniform motion problems are problems where an
object moves at a certain speed, or rate. Weighted Average
sum of estimate × weight
The formula d = rt is used to solve these = sum of weights
problems. In the formula, d represents
distance, r represents rate, and t represents
time. The average speed for the round
Answer trip was about 176.5 miles per
hour.

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