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Finding the Fourth Proportional to 261.46, 392.21 and 78.85

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Solution

The fourth proportional to 261.46, 392.21 and 78.85 is: 118.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.46 : 392.21 = 78.85 : x
  2. Step 2: Convert to fraction form
    261.46/392.21 = 78.85/x
  3. Step 3: Cross multiply
    261.46x = 392.21 × 78.85
  4. Step 4: Simplify right side
    261.46x = 30,925.76
  5. Step 5: Solve for x
    x = 30,925.76/261.46
  6. Step 6: Final answer
    x = 118.28

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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.