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Finding the Fourth Proportional to 991.40, 1,487.12 and 342.12

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Solution

The fourth proportional to 991.40, 1,487.12 and 342.12 is: 513.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.40 : 1,487.12 = 342.12 : x
  2. Step 2: Convert to fraction form
    991.40/1,487.12 = 342.12/x
  3. Step 3: Cross multiply
    991.40x = 1,487.12 × 342.12
  4. Step 4: Simplify right side
    991.40x = 508,773.49
  5. Step 5: Solve for x
    x = 508,773.49/991.40
  6. Step 6: Final answer
    x = 513.19

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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.