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Finding the Fourth Proportional to 1,188.42, 1,640.10 and 789.40

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Solution

The fourth proportional to 1,188.42, 1,640.10 and 789.40 is: 1,089.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,188.42 : 1,640.10 = 789.40 : x
  2. Step 2: Convert to fraction form
    1,188.42/1,640.10 = 789.40/x
  3. Step 3: Cross multiply
    1,188.42x = 1,640.10 × 789.40
  4. Step 4: Simplify right side
    1,188.42x = 1,294,686.28
  5. Step 5: Solve for x
    x = 1,294,686.28/1,188.42
  6. Step 6: Final answer
    x = 1,089.42

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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.