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Finding the Fourth Proportional to 1,390.70, 2,086.05 and 742.70

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Solution

The fourth proportional to 1,390.70, 2,086.05 and 742.70 is: 1,114.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.70 : 2,086.05 = 742.70 : x
  2. Step 2: Convert to fraction form
    1,390.70/2,086.05 = 742.70/x
  3. Step 3: Cross multiply
    1,390.70x = 2,086.05 × 742.70
  4. Step 4: Simplify right side
    1,390.70x = 1,549,309.34
  5. Step 5: Solve for x
    x = 1,549,309.34/1,390.70
  6. Step 6: Final answer
    x = 1,114.05

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.