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Finding the Fourth Proportional to 939.86, 1,410.20 and 870.20

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Solution

The fourth proportional to 939.86, 1,410.20 and 870.20 is: 1,305.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.86 : 1,410.20 = 870.20 : x
  2. Step 2: Convert to fraction form
    939.86/1,410.20 = 870.20/x
  3. Step 3: Cross multiply
    939.86x = 1,410.20 × 870.20
  4. Step 4: Simplify right side
    939.86x = 1,227,156.04
  5. Step 5: Solve for x
    x = 1,227,156.04/939.86
  6. Step 6: Final answer
    x = 1,305.68

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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.