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Finding the Fourth Proportional to 1,387.80, 1,915.16 and 766.80

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Solution

The fourth proportional to 1,387.80, 1,915.16 and 766.80 is: 1,058.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.80 : 1,915.16 = 766.80 : x
  2. Step 2: Convert to fraction form
    1,387.80/1,915.16 = 766.80/x
  3. Step 3: Cross multiply
    1,387.80x = 1,915.16 × 766.80
  4. Step 4: Simplify right side
    1,387.80x = 1,468,539.90
  5. Step 5: Solve for x
    x = 1,468,539.90/1,387.80
  6. Step 6: Final answer
    x = 1,058.18

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.