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Finding the Fourth Proportional to 1,247.10, 1,720.96 and 687.55

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Solution

The fourth proportional to 1,247.10, 1,720.96 and 687.55 is: 948.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.10 : 1,720.96 = 687.55 : x
  2. Step 2: Convert to fraction form
    1,247.10/1,720.96 = 687.55/x
  3. Step 3: Cross multiply
    1,247.10x = 1,720.96 × 687.55
  4. Step 4: Simplify right side
    1,247.10x = 1,183,246.05
  5. Step 5: Solve for x
    x = 1,183,246.05/1,247.10
  6. Step 6: Final answer
    x = 948.80

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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.