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Finding the Fourth Proportional to 1,247.39, 1,721.42 and 687.89

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Solution

The fourth proportional to 1,247.39, 1,721.42 and 687.89 is: 949.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.39 : 1,721.42 = 687.89 : x
  2. Step 2: Convert to fraction form
    1,247.39/1,721.42 = 687.89/x
  3. Step 3: Cross multiply
    1,247.39x = 1,721.42 × 687.89
  4. Step 4: Simplify right side
    1,247.39x = 1,184,135.56
  5. Step 5: Solve for x
    x = 1,184,135.56/1,247.39
  6. Step 6: Final answer
    x = 949.29

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.