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Finding the Fourth Proportional to 838.74, 1,258.88 and 428.18

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Solution

The fourth proportional to 838.74, 1,258.88 and 428.18 is: 642.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    838.74 : 1,258.88 = 428.18 : x
  2. Step 2: Convert to fraction form
    838.74/1,258.88 = 428.18/x
  3. Step 3: Cross multiply
    838.74x = 1,258.88 × 428.18
  4. Step 4: Simplify right side
    838.74x = 539,018.80
  5. Step 5: Solve for x
    x = 539,018.80/838.74
  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.