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Finding the Fourth Proportional to 355, 489.90 and 199.80

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Solution

The fourth proportional to 355, 489.90 and 199.80 is: 275.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    355 : 489.90 = 199.80 : x
  2. Step 2: Convert to fraction form
    355/489.90 = 199.80/x
  3. Step 3: Cross multiply
    355x = 489.90 × 199.80
  4. Step 4: Simplify right side
    355x = 97,882.02
  5. Step 5: Solve for x
    x = 97,882.02/355
  6. Step 6: Final answer
    x = 275.72

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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.