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Finding the Fourth Proportional to 908.50, 1,361.80 and 421.15

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Solution

The fourth proportional to 908.50, 1,361.80 and 421.15 is: 631.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    908.50 : 1,361.80 = 421.15 : x
  2. Step 2: Convert to fraction form
    908.50/1,361.80 = 421.15/x
  3. Step 3: Cross multiply
    908.50x = 1,361.80 × 421.15
  4. Step 4: Simplify right side
    908.50x = 573,513.16
  5. Step 5: Solve for x
    x = 573,513.16/908.50
  6. Step 6: Final answer
    x = 631.28

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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.