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Finding the Fourth Proportional to 991.90, 1,487.86 and 298.40

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Solution

The fourth proportional to 991.90, 1,487.86 and 298.40 is: 447.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.90 : 1,487.86 = 298.40 : x
  2. Step 2: Convert to fraction form
    991.90/1,487.86 = 298.40/x
  3. Step 3: Cross multiply
    991.90x = 1,487.86 × 298.40
  4. Step 4: Simplify right side
    991.90x = 443,977.42
  5. Step 5: Solve for x
    x = 443,977.42/991.90
  6. Step 6: Final answer
    x = 447.60

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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.