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Finding the Fourth Proportional to 862.40, 1,291.80 and 645.68

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Solution

The fourth proportional to 862.40, 1,291.80 and 645.68 is: 967.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    862.40 : 1,291.80 = 645.68 : x
  2. Step 2: Convert to fraction form
    862.40/1,291.80 = 645.68/x
  3. Step 3: Cross multiply
    862.40x = 1,291.80 × 645.68
  4. Step 4: Simplify right side
    862.40x = 834,089.42
  5. Step 5: Solve for x
    x = 834,089.42/862.40
  6. Step 6: Final answer
    x = 967.17

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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.