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Finding the Fourth Proportional to 998.40, 1,496.80 and 421.12

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Solution

The fourth proportional to 998.40, 1,496.80 and 421.12 is: 631.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.40 : 1,496.80 = 421.12 : x
  2. Step 2: Convert to fraction form
    998.40/1,496.80 = 421.12/x
  3. Step 3: Cross multiply
    998.40x = 1,496.80 × 421.12
  4. Step 4: Simplify right side
    998.40x = 630,332.42
  5. Step 5: Solve for x
    x = 630,332.42/998.40
  6. Step 6: Final answer
    x = 631.34

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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.