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Finding the Fourth Proportional to 987.84, 1,479.60 and 621.72

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Solution

The fourth proportional to 987.84, 1,479.60 and 621.72 is: 931.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.84 : 1,479.60 = 621.72 : x
  2. Step 2: Convert to fraction form
    987.84/1,479.60 = 621.72/x
  3. Step 3: Cross multiply
    987.84x = 1,479.60 × 621.72
  4. Step 4: Simplify right side
    987.84x = 919,896.91
  5. Step 5: Solve for x
    x = 919,896.91/987.84
  6. Step 6: Final answer
    x = 931.22

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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.