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Finding the Fourth Proportional to 1,987.32, 2,978.90 and 816.80

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Solution

The fourth proportional to 1,987.32, 2,978.90 and 816.80 is: 1,224.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.32 : 2,978.90 = 816.80 : x
  2. Step 2: Convert to fraction form
    1,987.32/2,978.90 = 816.80/x
  3. Step 3: Cross multiply
    1,987.32x = 2,978.90 × 816.80
  4. Step 4: Simplify right side
    1,987.32x = 2,433,165.52
  5. Step 5: Solve for x
    x = 2,433,165.52/1,987.32
  6. Step 6: Final answer
    x = 1,224.35

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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.