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Finding the Fourth Proportional to 991.40, 1,487.31 and 288.61

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Solution

The fourth proportional to 991.40, 1,487.31 and 288.61 is: 432.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.40 : 1,487.31 = 288.61 : x
  2. Step 2: Convert to fraction form
    991.40/1,487.31 = 288.61/x
  3. Step 3: Cross multiply
    991.40x = 1,487.31 × 288.61
  4. Step 4: Simplify right side
    991.40x = 429,252.54
  5. Step 5: Solve for x
    x = 429,252.54/991.40
  6. Step 6: Final answer
    x = 432.98

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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.