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Finding the Fourth Proportional to 1,387.80, 2,081.70 and 618.12

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Solution

The fourth proportional to 1,387.80, 2,081.70 and 618.12 is: 927.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.80 : 2,081.70 = 618.12 : x
  2. Step 2: Convert to fraction form
    1,387.80/2,081.70 = 618.12/x
  3. Step 3: Cross multiply
    1,387.80x = 2,081.70 × 618.12
  4. Step 4: Simplify right side
    1,387.80x = 1,286,740.40
  5. Step 5: Solve for x
    x = 1,286,740.40/1,387.80
  6. Step 6: Final answer
    x = 927.18

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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.