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Finding the Fourth Proportional to 818.19, 1,227.38 and 428.40

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Solution

The fourth proportional to 818.19, 1,227.38 and 428.40 is: 642.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    818.19 : 1,227.38 = 428.40 : x
  2. Step 2: Convert to fraction form
    818.19/1,227.38 = 428.40/x
  3. Step 3: Cross multiply
    818.19x = 1,227.38 × 428.40
  4. Step 4: Simplify right side
    818.19x = 525,807.45
  5. Step 5: Solve for x
    x = 525,807.45/818.19
  6. Step 6: Final answer
    x = 642.65

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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.