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Finding the Fourth Proportional to 1,240.75, 1,712.31 and 716.78

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Solution

The fourth proportional to 1,240.75, 1,712.31 and 716.78 is: 989.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,240.75 : 1,712.31 = 716.78 : x
  2. Step 2: Convert to fraction form
    1,240.75/1,712.31 = 716.78/x
  3. Step 3: Cross multiply
    1,240.75x = 1,712.31 × 716.78
  4. Step 4: Simplify right side
    1,240.75x = 1,227,351.15
  5. Step 5: Solve for x
    x = 1,227,351.15/1,240.75
  6. Step 6: Final answer
    x = 989.20

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Find fourth proportional to 620.38, 856.15 and 358.39
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.