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Finding the Fourth Proportional to 1,078.76, 1,618.40 and 640.39

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Solution

The fourth proportional to 1,078.76, 1,618.40 and 640.39 is: 960.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,078.76 : 1,618.40 = 640.39 : x
  2. Step 2: Convert to fraction form
    1,078.76/1,618.40 = 640.39/x
  3. Step 3: Cross multiply
    1,078.76x = 1,618.40 × 640.39
  4. Step 4: Simplify right side
    1,078.76x = 1,036,407.20
  5. Step 5: Solve for x
    x = 1,036,407.20/1,078.76
  6. Step 6: Final answer
    x = 960.74

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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.