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Finding the Fourth Proportional to 854.80, 1,279.80 and 661.20

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Solution

The fourth proportional to 854.80, 1,279.80 and 661.20 is: 989.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    854.80 : 1,279.80 = 661.20 : x
  2. Step 2: Convert to fraction form
    854.80/1,279.80 = 661.20/x
  3. Step 3: Cross multiply
    854.80x = 1,279.80 × 661.20
  4. Step 4: Simplify right side
    854.80x = 846,203.76
  5. Step 5: Solve for x
    x = 846,203.76/854.80
  6. Step 6: Final answer
    x = 989.94

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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.