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Finding the Fourth Proportional to 1,387.82, 1,917.92 and 1,240.20

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Solution

The fourth proportional to 1,387.82, 1,917.92 and 1,240.20 is: 1,713.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.82 : 1,917.92 = 1,240.20 : x
  2. Step 2: Convert to fraction form
    1,387.82/1,917.92 = 1,240.20/x
  3. Step 3: Cross multiply
    1,387.82x = 1,917.92 × 1,240.20
  4. Step 4: Simplify right side
    1,387.82x = 2,378,604.38
  5. Step 5: Solve for x
    x = 2,378,604.38/1,387.82
  6. Step 6: Final answer
    x = 1,713.91

Related Problems

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Half scale
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Double scale
Find fourth proportional to 1,388.82, 1,919.30 and 1,241.20
Similar ratio
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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.