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Finding the Fourth Proportional to 261.63, 390.42 and 255.15

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Solution

The fourth proportional to 261.63, 390.42 and 255.15 is: 380.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.63 : 390.42 = 255.15 : x
  2. Step 2: Convert to fraction form
    261.63/390.42 = 255.15/x
  3. Step 3: Cross multiply
    261.63x = 390.42 × 255.15
  4. Step 4: Simplify right side
    261.63x = 99,615.66
  5. Step 5: Solve for x
    x = 99,615.66/261.63
  6. Step 6: Final answer
    x = 380.75

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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.