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Finding the Fourth Proportional to 987.80, 1,479.26 and 931.91

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Solution

The fourth proportional to 987.80, 1,479.26 and 931.91 is: 1,395.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.80 : 1,479.26 = 931.91 : x
  2. Step 2: Convert to fraction form
    987.80/1,479.26 = 931.91/x
  3. Step 3: Cross multiply
    987.80x = 1,479.26 × 931.91
  4. Step 4: Simplify right side
    987.80x = 1,378,532.12
  5. Step 5: Solve for x
    x = 1,378,532.12/987.80
  6. Step 6: Final answer
    x = 1,395.56

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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.