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Finding the Fourth Proportional to 86.90, 130.19 and 61.17

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Solution

The fourth proportional to 86.90, 130.19 and 61.17 is: 91.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.90 : 130.19 = 61.17 : x
  2. Step 2: Convert to fraction form
    86.90/130.19 = 61.17/x
  3. Step 3: Cross multiply
    86.90x = 130.19 × 61.17
  4. Step 4: Simplify right side
    86.90x = 7,963.42
  5. Step 5: Solve for x
    x = 7,963.42/86.90
  6. Step 6: Final answer
    x = 91.64

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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.