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Finding the Fourth Proportional to 891.60, 1,229.40 and 642.12

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Solution

The fourth proportional to 891.60, 1,229.40 and 642.12 is: 885.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.60 : 1,229.40 = 642.12 : x
  2. Step 2: Convert to fraction form
    891.60/1,229.40 = 642.12/x
  3. Step 3: Cross multiply
    891.60x = 1,229.40 × 642.12
  4. Step 4: Simplify right side
    891.60x = 789,422.33
  5. Step 5: Solve for x
    x = 789,422.33/891.60
  6. Step 6: Final answer
    x = 885.40

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1.5x scale

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.