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Finding the Fourth Proportional to 1,987.20, 2,978.92 and 946.65

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Solution

The fourth proportional to 1,987.20, 2,978.92 and 946.65 is: 1,419.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.20 : 2,978.92 = 946.65 : x
  2. Step 2: Convert to fraction form
    1,987.20/2,978.92 = 946.65/x
  3. Step 3: Cross multiply
    1,987.20x = 2,978.92 × 946.65
  4. Step 4: Simplify right side
    1,987.20x = 2,819,989.88
  5. Step 5: Solve for x
    x = 2,819,989.88/1,987.20
  6. Step 6: Final answer
    x = 1,419.08

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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.