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Finding the Fourth Proportional to 378.70, 520.95 and 311.50

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Solution

The fourth proportional to 378.70, 520.95 and 311.50 is: 428.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    378.70 : 520.95 = 311.50 : x
  2. Step 2: Convert to fraction form
    378.70/520.95 = 311.50/x
  3. Step 3: Cross multiply
    378.70x = 520.95 × 311.50
  4. Step 4: Simplify right side
    378.70x = 162,275.93
  5. Step 5: Solve for x
    x = 162,275.93/378.70
  6. Step 6: Final answer
    x = 428.51

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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.