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Finding the Fourth Proportional to 861.06, 1,188.51 and 640.74

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Solution

The fourth proportional to 861.06, 1,188.51 and 640.74 is: 884.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.06 : 1,188.51 = 640.74 : x
  2. Step 2: Convert to fraction form
    861.06/1,188.51 = 640.74/x
  3. Step 3: Cross multiply
    861.06x = 1,188.51 × 640.74
  4. Step 4: Simplify right side
    861.06x = 761,525.90
  5. Step 5: Solve for x
    x = 761,525.90/861.06
  6. Step 6: Final answer
    x = 884.41

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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.