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Finding the Fourth Proportional to 128.08, 191.32 and 91.72

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Solution

The fourth proportional to 128.08, 191.32 and 91.72 is: 137.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.08 : 191.32 = 91.72 : x
  2. Step 2: Convert to fraction form
    128.08/191.32 = 91.72/x
  3. Step 3: Cross multiply
    128.08x = 191.32 × 91.72
  4. Step 4: Simplify right side
    128.08x = 17,547.87
  5. Step 5: Solve for x
    x = 17,547.87/128.08
  6. Step 6: Final answer
    x = 137.01

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.