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Finding the Fourth Proportional to 853.72, 1,279.60 and 421.20

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Solution

The fourth proportional to 853.72, 1,279.60 and 421.20 is: 631.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.72 : 1,279.60 = 421.20 : x
  2. Step 2: Convert to fraction form
    853.72/1,279.60 = 421.20/x
  3. Step 3: Cross multiply
    853.72x = 1,279.60 × 421.20
  4. Step 4: Simplify right side
    853.72x = 538,967.52
  5. Step 5: Solve for x
    x = 538,967.52/853.72
  6. Step 6: Final answer
    x = 631.32

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1.5x scale

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.