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Finding the Fourth Proportional to 1,411.76, 2,115.80 and 978

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Solution

The fourth proportional to 1,411.76, 2,115.80 and 978 is: 1,465.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,411.76 : 2,115.80 = 978 : x
  2. Step 2: Convert to fraction form
    1,411.76/2,115.80 = 978/x
  3. Step 3: Cross multiply
    1,411.76x = 2,115.80 × 978
  4. Step 4: Simplify right side
    1,411.76x = 2,069,252.40
  5. Step 5: Solve for x
    x = 2,069,252.40/1,411.76
  6. Step 6: Final answer
    x = 1,465.73

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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.