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Finding the Fourth Proportional to 824.20, 1,242.75 and 721.80

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Solution

The fourth proportional to 824.20, 1,242.75 and 721.80 is: 1,088.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    824.20 : 1,242.75 = 721.80 : x
  2. Step 2: Convert to fraction form
    824.20/1,242.75 = 721.80/x
  3. Step 3: Cross multiply
    824.20x = 1,242.75 × 721.80
  4. Step 4: Simplify right side
    824.20x = 897,016.95
  5. Step 5: Solve for x
    x = 897,016.95/824.20
  6. Step 6: Final answer
    x = 1,088.35

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.