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Finding the Fourth Proportional to 891.60, 1,229.74 and 643.74

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Solution

The fourth proportional to 891.60, 1,229.74 and 643.74 is: 887.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.60 : 1,229.74 = 643.74 : x
  2. Step 2: Convert to fraction form
    891.60/1,229.74 = 643.74/x
  3. Step 3: Cross multiply
    891.60x = 1,229.74 × 643.74
  4. Step 4: Simplify right side
    891.60x = 791,632.83
  5. Step 5: Solve for x
    x = 791,632.83/891.60
  6. Step 6: Final answer
    x = 887.88

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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.