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Finding the Fourth Proportional to 678.42, 935.90 and 398.57

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Solution

The fourth proportional to 678.42, 935.90 and 398.57 is: 549.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.42 : 935.90 = 398.57 : x
  2. Step 2: Convert to fraction form
    678.42/935.90 = 398.57/x
  3. Step 3: Cross multiply
    678.42x = 935.90 × 398.57
  4. Step 4: Simplify right side
    678.42x = 373,017.98
  5. Step 5: Solve for x
    x = 373,017.98/678.42
  6. Step 6: Final answer
    x = 549.83

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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.