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Finding the Fourth Proportional to 987.66, 1,363.28 and 638.28

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Solution

The fourth proportional to 987.66, 1,363.28 and 638.28 is: 881.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.66 : 1,363.28 = 638.28 : x
  2. Step 2: Convert to fraction form
    987.66/1,363.28 = 638.28/x
  3. Step 3: Cross multiply
    987.66x = 1,363.28 × 638.28
  4. Step 4: Simplify right side
    987.66x = 870,151.17
  5. Step 5: Solve for x
    x = 870,151.17/987.66
  6. Step 6: Final answer
    x = 881.02

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.