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Finding the Fourth Proportional to 991.38, 1,487.31 and 342.12

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Solution

The fourth proportional to 991.38, 1,487.31 and 342.12 is: 513.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.38 : 1,487.31 = 342.12 : x
  2. Step 2: Convert to fraction form
    991.38/1,487.31 = 342.12/x
  3. Step 3: Cross multiply
    991.38x = 1,487.31 × 342.12
  4. Step 4: Simplify right side
    991.38x = 508,837.21
  5. Step 5: Solve for x
    x = 508,837.21/991.38
  6. Step 6: Final answer
    x = 513.26

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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.