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Finding the Fourth Proportional to 99.40, 136.98 and 91.72

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Solution

The fourth proportional to 99.40, 136.98 and 91.72 is: 126.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.40 : 136.98 = 91.72 : x
  2. Step 2: Convert to fraction form
    99.40/136.98 = 91.72/x
  3. Step 3: Cross multiply
    99.40x = 136.98 × 91.72
  4. Step 4: Simplify right side
    99.40x = 12,563.81
  5. Step 5: Solve for x
    x = 12,563.81/99.40
  6. Step 6: Final answer
    x = 126.40

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.