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Finding the Third Proportional to 117.42 and 128.18

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Solution

The third proportional to 117.42 and 128.18 is: 139.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    117.42 : 128.18 = 128.18 : x
  2. Step 2: Convert to fraction form
    117.42/128.18 = 128.18/x
  3. Step 3: Cross multiply
    117.42x = 128.18 × 128.18
  4. Step 4: Simplify right side
    117.42x = 16,430.03
  5. Step 5: Solve for x
    x = 16,430.03/117.42
  6. Step 6: Final answer
    x = 139.92

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Why These Related Problems?

These problems maintain the same ratio (1.09) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.