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Finding the Fourth Proportional to 86.72, 130.16 and 78.22

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Solution

The fourth proportional to 86.72, 130.16 and 78.22 is: 117.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.72 : 130.16 = 78.22 : x
  2. Step 2: Convert to fraction form
    86.72/130.16 = 78.22/x
  3. Step 3: Cross multiply
    86.72x = 130.16 × 78.22
  4. Step 4: Simplify right side
    86.72x = 10,181.12
  5. Step 5: Solve for x
    x = 10,181.12/86.72
  6. Step 6: Final answer
    x = 117.40

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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.