Math Problem Statement

Amy is riding a bicycle with tires that have a radius of 28 cm. If the tires have made 1,250 revolutions since she started, how far has she traveled? Give your answer in km and use 22/7 for pi.

Solution

To determine how far Amy has traveled, we first need to calculate the distance covered in one revolution of the bicycle tire, then multiply that by the total number of revolutions.

Step 1: Circumference of the tire

The distance covered in one revolution of the tire is the tire's circumference. The formula for the circumference of a circle is:

C=2πrC = 2 \pi r

Where:

  • CC is the circumference
  • rr is the radius of the tire
  • π\pi is approximated as 227\frac{22}{7}

Given:

  • r=28r = 28 cm
  • π=227\pi = \frac{22}{7}

Now, substitute the values:

C=2×227×28=2×88=176cmC = 2 \times \frac{22}{7} \times 28 = 2 \times 88 = 176 \, \text{cm}

Step 2: Total distance traveled

To find the total distance Amy traveled, multiply the circumference by the number of revolutions:

Total distance=C×number of revolutions=176cm×1250=220000cm\text{Total distance} = C \times \text{number of revolutions} = 176 \, \text{cm} \times 1250 = 220000 \, \text{cm}

Step 3: Convert to kilometers

Now, convert the total distance from centimeters to kilometers:

1km=1000m=100000cm1 \, \text{km} = 1000 \, \text{m} = 100000 \, \text{cm}

So,

Total distance in kilometers=220000100000=2.2km\text{Total distance in kilometers} = \frac{220000}{100000} = 2.2 \, \text{km}

Final Answer:

Amy has traveled 2.2 km.

Would you like further clarification, or do you have any questions?

Here are 5 related questions for deeper exploration:

  1. What would be the distance traveled if the tire radius was increased to 35 cm?
  2. How many revolutions would Amy need to make to travel 5 km?
  3. If Amy increases her speed, how does that affect the number of tire revolutions over a fixed distance?
  4. How does the radius of the tire affect the number of revolutions needed to travel a fixed distance?
  5. If Amy’s tire circumference was measured in meters, how would the calculation change?

Tip: Always remember that the circumference of a circle directly affects how far an object travels per revolution. Larger wheels cover more distance per turn!

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Math Problem Analysis

Mathematical Concepts

Geometry
Circumference of a Circle
Unit Conversion
Multiplication

Formulas

Circumference of a circle: C = 2 * pi * r
Unit conversion: 1 km = 100000 cm

Theorems

Formula for the circumference of a circle

Suitable Grade Level

Grades 6-8