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Finding the Fourth Proportional to 988.12, 1,362.18 and 638.20

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Solution

The fourth proportional to 988.12, 1,362.18 and 638.20 is: 879.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    988.12 : 1,362.18 = 638.20 : x
  2. Step 2: Convert to fraction form
    988.12/1,362.18 = 638.20/x
  3. Step 3: Cross multiply
    988.12x = 1,362.18 × 638.20
  4. Step 4: Simplify right side
    988.12x = 869,343.28
  5. Step 5: Solve for x
    x = 869,343.28/988.12
  6. Step 6: Final answer
    x = 879.80

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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.