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Finding the Fourth Proportional to 818.55, 1,227.51 and 428.25

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Solution

The fourth proportional to 818.55, 1,227.51 and 428.25 is: 642.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    818.55 : 1,227.51 = 428.25 : x
  2. Step 2: Convert to fraction form
    818.55/1,227.51 = 428.25/x
  3. Step 3: Cross multiply
    818.55x = 1,227.51 × 428.25
  4. Step 4: Simplify right side
    818.55x = 525,681.16
  5. Step 5: Solve for x
    x = 525,681.16/818.55
  6. Step 6: Final answer
    x = 642.21

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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.