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Finding the Fourth Proportional to 399.15, 549.54 and 378.65

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Solution

The fourth proportional to 399.15, 549.54 and 378.65 is: 521.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.15 : 549.54 = 378.65 : x
  2. Step 2: Convert to fraction form
    399.15/549.54 = 378.65/x
  3. Step 3: Cross multiply
    399.15x = 549.54 × 378.65
  4. Step 4: Simplify right side
    399.15x = 208,084.69
  5. Step 5: Solve for x
    x = 208,084.69/399.15
  6. Step 6: Final answer
    x = 521.32

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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.