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Finding the Fourth Proportional to 870.21, 1,305.11 and 253.90

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Solution

The fourth proportional to 870.21, 1,305.11 and 253.90 is: 380.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.21 : 1,305.11 = 253.90 : x
  2. Step 2: Convert to fraction form
    870.21/1,305.11 = 253.90/x
  3. Step 3: Cross multiply
    870.21x = 1,305.11 × 253.90
  4. Step 4: Simplify right side
    870.21x = 331,369.70
  5. Step 5: Solve for x
    x = 331,369.70/870.21
  6. Step 6: Final answer
    x = 380.79

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.