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Finding the Fourth Proportional to 891.18, 1,229.65 and 642.87

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Solution

The fourth proportional to 891.18, 1,229.65 and 642.87 is: 887.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.18 : 1,229.65 = 642.87 : x
  2. Step 2: Convert to fraction form
    891.18/1,229.65 = 642.87/x
  3. Step 3: Cross multiply
    891.18x = 1,229.65 × 642.87
  4. Step 4: Simplify right side
    891.18x = 790,503.49
  5. Step 5: Solve for x
    x = 790,503.49/891.18
  6. Step 6: Final answer
    x = 887.03

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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.