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Finding the Fourth Proportional to 1,187.80, 1,781.98 and 457.40

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Solution

The fourth proportional to 1,187.80, 1,781.98 and 457.40 is: 686.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.80 : 1,781.98 = 457.40 : x
  2. Step 2: Convert to fraction form
    1,187.80/1,781.98 = 457.40/x
  3. Step 3: Cross multiply
    1,187.80x = 1,781.98 × 457.40
  4. Step 4: Simplify right side
    1,187.80x = 815,077.65
  5. Step 5: Solve for x
    x = 815,077.65/1,187.80
  6. Step 6: Final answer
    x = 686.21

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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.