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Finding the Fourth Proportional to 261.21, 390.43 and 199.70

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Solution

The fourth proportional to 261.21, 390.43 and 199.70 is: 298.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.21 : 390.43 = 199.70 : x
  2. Step 2: Convert to fraction form
    261.21/390.43 = 199.70/x
  3. Step 3: Cross multiply
    261.21x = 390.43 × 199.70
  4. Step 4: Simplify right side
    261.21x = 77,968.87
  5. Step 5: Solve for x
    x = 77,968.87/261.21
  6. Step 6: Final answer
    x = 298.49

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.