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Finding the Fourth Proportional to 782.40, 1,175.20 and 688.40

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Solution

The fourth proportional to 782.40, 1,175.20 and 688.40 is: 1,034.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    782.40 : 1,175.20 = 688.40 : x
  2. Step 2: Convert to fraction form
    782.40/1,175.20 = 688.40/x
  3. Step 3: Cross multiply
    782.40x = 1,175.20 × 688.40
  4. Step 4: Simplify right side
    782.40x = 809,007.68
  5. Step 5: Solve for x
    x = 809,007.68/782.40
  6. Step 6: Final answer
    x = 1,034.01

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.