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Finding the Fourth Proportional to 261.44, 390.40 and 212.76

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Solution

The fourth proportional to 261.44, 390.40 and 212.76 is: 317.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.44 : 390.40 = 212.76 : x
  2. Step 2: Convert to fraction form
    261.44/390.40 = 212.76/x
  3. Step 3: Cross multiply
    261.44x = 390.40 × 212.76
  4. Step 4: Simplify right side
    261.44x = 83,061.50
  5. Step 5: Solve for x
    x = 83,061.50/261.44
  6. Step 6: Final answer
    x = 317.71

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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.