To solve these problems using cross multiplication, we will set up proportions for each problem and solve them step by step. Let's go through each question:
---
Problem 1:
A truck covers 432 miles in 36 gallons of fuel. How much distance would it cover in 25 gallons of fuel?
#### Step 1: Set up the proportion
The relationship between distance and fuel is proportional:
\[
\frac{\text{Distance}}{\text{Fuel}} = \frac{\text{Distance}}{\text{Fuel}}
\]
Given:
\[
\frac{432 \text{ miles}}{36 \text{ gallons}} = \frac{x \text{ miles}}{25 \text{ gallons}}
\]
#### Step 2: Cross-multiply
\[
432 \times 25 = 36 \times x
\]
#### Step 3: Solve for \( x \)
\[
10800 = 36x
\]
\[
x = \frac{10800}{36}
\]
\[
x = 300
\]
#### Answer:
\[
\boxed{300 \text{ miles}}
\]
---
Problem 2:
A factory can produce 20 boxes of pencils in a minute. How many boxes does the factory make in 30 minutes?
#### Step 1: Set up the proportion
The relationship between time and production is proportional:
\[
\frac{\text{Boxes}}{\text{Time}} = \frac{\text{Boxes}}{\text{Time}}
\]
Given:
\[
\frac{20 \text{ boxes}}{1 \text{ minute}} = \frac{x \text{ boxes}}{30 \text{ minutes}}
\]
#### Step 2: Cross-multiply
\[
20 \times 30 = 1 \times x
\]
#### Step 3: Solve for \( x \)
\[
x = 600
\]
#### Answer:
\[
\boxed{600 \text{ boxes}}
\]
---
Problem 3:
A taxi charges a fare of $1275 for a journey of 150 miles. How much would it charge for a journey of 124 miles?
#### Step 1: Set up the proportion
The relationship between fare and distance is proportional:
\[
\frac{\text{Fare}}{\text{Distance}} = \frac{\text{Fare}}{\text{Distance}}
\]
Given:
\[
\frac{1275 \text{ dollars}}{150 \text{ miles}} = \frac{x \text{ dollars}}{124 \text{ miles}}
\]
#### Step 2: Cross-multiply
\[
1275 \times 124 = 150 \times x
\]
#### Step 3: Solve for \( x \)
\[
158100 = 150x
\]
\[
x = \frac{158100}{150}
\]
\[
x = 1054
\]
#### Answer:
\[
\boxed{1054 \text{ dollars}}
\]
---
Problem 4:
If 8 apples cost $4, how much would 40 apples cost?
#### Step 1: Set up the proportion
The relationship between the number of apples and cost is proportional:
\[
\frac{\text{Apples}}{\text{Cost}} = \frac{\text{Apples}}{\text{Cost}}
\]
Given:
\[
\frac{8 \text{ apples}}{4 \text{ dollars}} = \frac{40 \text{ apples}}{x \text{ dollars}}
\]
#### Step 2: Cross-multiply
\[
8 \times x = 4 \times 40
\]
#### Step 3: Solve for \( x \)
\[
8x = 160
\]
\[
x = \frac{160}{8}
\]
\[
x = 20
\]
#### Answer:
\[
\boxed{20 \text{ dollars}}
\]
---
Problem 5:
A ship covers 16 miles in 25 minutes. At the same speed, how far can it travel in 5 hours?
#### Step 1: Convert 5 hours to minutes
Since there are 60 minutes in an hour:
\[
5 \text{ hours} = 5 \times 60 = 300 \text{ minutes}
\]
#### Step 2: Set up the proportion
The relationship between distance and time is proportional:
\[
\frac{\text{Distance}}{\text{Time}} = \frac{\text{Distance}}{\text{Time}}
\]
Given:
\[
\frac{16 \text{ miles}}{25 \text{ minutes}} = \frac{x \text{ miles}}{300 \text{ minutes}}
\]
#### Step 3: Cross-multiply
\[
16 \times 300 = 25 \times x
\]
#### Step 4: Solve for \( x \)
\[
4800 = 25x
\]
\[
x = \frac{4800}{25}
\]
\[
x = 192
\]
#### Answer:
\[
\boxed{192 \text{ miles}}
\]
---
Final Answers:
1. \(\boxed{300 \text{ miles}}\)
2. \(\boxed{600 \text{ boxes}}\)
3. \(\boxed{1054 \text{ dollars}}\)
4. \(\boxed{20 \text{ dollars}}\)
5. \(\boxed{192 \text{ miles}}\)
Parent Tip: Review the logic above to help your child master the concept of cross multiplication word problems worksheet.