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Finding the Fourth Proportional to 355, 489.90 and 199.78

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Solution

The fourth proportional to 355, 489.90 and 199.78 is: 275.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    355 : 489.90 = 199.78 : x
  2. Step 2: Convert to fraction form
    355/489.90 = 199.78/x
  3. Step 3: Cross multiply
    355x = 489.90 × 199.78
  4. Step 4: Simplify right side
    355x = 97,872.22
  5. Step 5: Solve for x
    x = 97,872.22/355
  6. Step 6: Final answer
    x = 275.70

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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.