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Finding the Fourth Proportional to 718.38, 1,070.42 and 641.78

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Solution

The fourth proportional to 718.38, 1,070.42 and 641.78 is: 956.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.38 : 1,070.42 = 641.78 : x
  2. Step 2: Convert to fraction form
    718.38/1,070.42 = 641.78/x
  3. Step 3: Cross multiply
    718.38x = 1,070.42 × 641.78
  4. Step 4: Simplify right side
    718.38x = 686,974.15
  5. Step 5: Solve for x
    x = 686,974.15/718.38
  6. Step 6: Final answer
    x = 956.28

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.