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Finding the Fourth Proportional to 1,247.95, 1,722.12 and 688.40

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Solution

The fourth proportional to 1,247.95, 1,722.12 and 688.40 is: 949.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.95 : 1,722.12 = 688.40 : x
  2. Step 2: Convert to fraction form
    1,247.95/1,722.12 = 688.40/x
  3. Step 3: Cross multiply
    1,247.95x = 1,722.12 × 688.40
  4. Step 4: Simplify right side
    1,247.95x = 1,185,507.41
  5. Step 5: Solve for x
    x = 1,185,507.41/1,247.95
  6. Step 6: Final answer
    x = 949.97

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Half scale
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Double scale
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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.