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Finding the Fourth Proportional to 1,120.79, 1,680.78 and 427.11

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Solution

The fourth proportional to 1,120.79, 1,680.78 and 427.11 is: 640.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,120.79 : 1,680.78 = 427.11 : x
  2. Step 2: Convert to fraction form
    1,120.79/1,680.78 = 427.11/x
  3. Step 3: Cross multiply
    1,120.79x = 1,680.78 × 427.11
  4. Step 4: Simplify right side
    1,120.79x = 717,877.95
  5. Step 5: Solve for x
    x = 717,877.95/1,120.79
  6. Step 6: Final answer
    x = 640.51

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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.