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Finding the Fourth Proportional to 987.88, 1,479.42 and 842.20

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Solution

The fourth proportional to 987.88, 1,479.42 and 842.20 is: 1,261.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.88 : 1,479.42 = 842.20 : x
  2. Step 2: Convert to fraction form
    987.88/1,479.42 = 842.20/x
  3. Step 3: Cross multiply
    987.88x = 1,479.42 × 842.20
  4. Step 4: Simplify right side
    987.88x = 1,245,967.52
  5. Step 5: Solve for x
    x = 1,245,967.52/987.88
  6. Step 6: Final answer
    x = 1,261.25

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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.