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Finding the Fourth Proportional to 779.76, 1,074.96 and 639.18

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Solution

The fourth proportional to 779.76, 1,074.96 and 639.18 is: 881.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    779.76 : 1,074.96 = 639.18 : x
  2. Step 2: Convert to fraction form
    779.76/1,074.96 = 639.18/x
  3. Step 3: Cross multiply
    779.76x = 1,074.96 × 639.18
  4. Step 4: Simplify right side
    779.76x = 687,092.93
  5. Step 5: Solve for x
    x = 687,092.93/779.76
  6. Step 6: Final answer
    x = 881.16

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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.