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Finding the Fourth Proportional to 1,187.78, 1,781.66 and 640.22

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Solution

The fourth proportional to 1,187.78, 1,781.66 and 640.22 is: 960.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.78 : 1,781.66 = 640.22 : x
  2. Step 2: Convert to fraction form
    1,187.78/1,781.66 = 640.22/x
  3. Step 3: Cross multiply
    1,187.78x = 1,781.66 × 640.22
  4. Step 4: Simplify right side
    1,187.78x = 1,140,647.06
  5. Step 5: Solve for x
    x = 1,140,647.06/1,187.78
  6. Step 6: Final answer
    x = 960.32

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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.