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Finding the Fourth Proportional to 790.38, 1,090.62 and 642.78

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Solution

The fourth proportional to 790.38, 1,090.62 and 642.78 is: 886.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    790.38 : 1,090.62 = 642.78 : x
  2. Step 2: Convert to fraction form
    790.38/1,090.62 = 642.78/x
  3. Step 3: Cross multiply
    790.38x = 1,090.62 × 642.78
  4. Step 4: Simplify right side
    790.38x = 701,028.72
  5. Step 5: Solve for x
    x = 701,028.72/790.38
  6. Step 6: Final answer
    x = 886.95

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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.