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Finding the Fourth Proportional to 1,319.38, 1,978.42 and 771.74

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Solution

The fourth proportional to 1,319.38, 1,978.42 and 771.74 is: 1,157.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.38 : 1,978.42 = 771.74 : x
  2. Step 2: Convert to fraction form
    1,319.38/1,978.42 = 771.74/x
  3. Step 3: Cross multiply
    1,319.38x = 1,978.42 × 771.74
  4. Step 4: Simplify right side
    1,319.38x = 1,526,825.85
  5. Step 5: Solve for x
    x = 1,526,825.85/1,319.38
  6. Step 6: Final answer
    x = 1,157.23

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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.