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Finding the Fourth Proportional to 842.40, 1,279.80 and 842.40

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Solution

The fourth proportional to 842.40, 1,279.80 and 842.40 is: 1,279.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    842.40 : 1,279.80 = 842.40 : x
  2. Step 2: Convert to fraction form
    842.40/1,279.80 = 842.40/x
  3. Step 3: Cross multiply
    842.40x = 1,279.80 × 842.40
  4. Step 4: Simplify right side
    842.40x = 1,078,103.52
  5. Step 5: Solve for x
    x = 1,078,103.52/842.40
  6. Step 6: Final answer
    x = 1,279.80

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.52) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.