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Finding the Fourth Proportional to 908.12, 1,361.82 and 421.40

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Solution

The fourth proportional to 908.12, 1,361.82 and 421.40 is: 631.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    908.12 : 1,361.82 = 421.40 : x
  2. Step 2: Convert to fraction form
    908.12/1,361.82 = 421.40/x
  3. Step 3: Cross multiply
    908.12x = 1,361.82 × 421.40
  4. Step 4: Simplify right side
    908.12x = 573,870.95
  5. Step 5: Solve for x
    x = 573,870.95/908.12
  6. Step 6: Final answer
    x = 631.93

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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.