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Finding the Fourth Proportional to 991.40, 1,487.22 and 342.20

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Solution

The fourth proportional to 991.40, 1,487.22 and 342.20 is: 513.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.40 : 1,487.22 = 342.20 : x
  2. Step 2: Convert to fraction form
    991.40/1,487.22 = 342.20/x
  3. Step 3: Cross multiply
    991.40x = 1,487.22 × 342.20
  4. Step 4: Simplify right side
    991.40x = 508,926.68
  5. Step 5: Solve for x
    x = 508,926.68/991.40
  6. Step 6: Final answer
    x = 513.34

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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.