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Finding the Fourth Proportional to 938.48, 1,409.80 and 813.20

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Solution

The fourth proportional to 938.48, 1,409.80 and 813.20 is: 1,221.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.48 : 1,409.80 = 813.20 : x
  2. Step 2: Convert to fraction form
    938.48/1,409.80 = 813.20/x
  3. Step 3: Cross multiply
    938.48x = 1,409.80 × 813.20
  4. Step 4: Simplify right side
    938.48x = 1,146,449.36
  5. Step 5: Solve for x
    x = 1,146,449.36/938.48
  6. Step 6: Final answer
    x = 1,221.60

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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.