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Finding the Fourth Proportional to 987.72, 1,479.93 and 640.62

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Solution

The fourth proportional to 987.72, 1,479.93 and 640.62 is: 959.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.72 : 1,479.93 = 640.62 : x
  2. Step 2: Convert to fraction form
    987.72/1,479.93 = 640.62/x
  3. Step 3: Cross multiply
    987.72x = 1,479.93 × 640.62
  4. Step 4: Simplify right side
    987.72x = 948,072.76
  5. Step 5: Solve for x
    x = 948,072.76/987.72
  6. Step 6: Final answer
    x = 959.86

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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.