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Finding the Fourth Proportional to 1,208.39, 1,812.90 and 428.36

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Solution

The fourth proportional to 1,208.39, 1,812.90 and 428.36 is: 642.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,208.39 : 1,812.90 = 428.36 : x
  2. Step 2: Convert to fraction form
    1,208.39/1,812.90 = 428.36/x
  3. Step 3: Cross multiply
    1,208.39x = 1,812.90 × 428.36
  4. Step 4: Simplify right side
    1,208.39x = 776,573.84
  5. Step 5: Solve for x
    x = 776,573.84/1,208.39
  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.