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Finding the Fourth Proportional to 1,247.40, 1,721.49 and 687.87

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Solution

The fourth proportional to 1,247.40, 1,721.49 and 687.87 is: 949.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.40 : 1,721.49 = 687.87 : x
  2. Step 2: Convert to fraction form
    1,247.40/1,721.49 = 687.87/x
  3. Step 3: Cross multiply
    1,247.40x = 1,721.49 × 687.87
  4. Step 4: Simplify right side
    1,247.40x = 1,184,166.06
  5. Step 5: Solve for x
    x = 1,184,166.06/1,247.40
  6. Step 6: Final answer
    x = 949.30

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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.