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Finding the Fourth Proportional to 378.78, 521.58 and 356.86

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Solution

The fourth proportional to 378.78, 521.58 and 356.86 is: 491.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    378.78 : 521.58 = 356.86 : x
  2. Step 2: Convert to fraction form
    378.78/521.58 = 356.86/x
  3. Step 3: Cross multiply
    378.78x = 521.58 × 356.86
  4. Step 4: Simplify right side
    378.78x = 186,131.04
  5. Step 5: Solve for x
    x = 186,131.04/378.78
  6. Step 6: Final answer
    x = 491.40

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.