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Finding the Fourth Proportional to 828.80, 1,240.80 and 742.40

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Solution

The fourth proportional to 828.80, 1,240.80 and 742.40 is: 1,111.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    828.80 : 1,240.80 = 742.40 : x
  2. Step 2: Convert to fraction form
    828.80/1,240.80 = 742.40/x
  3. Step 3: Cross multiply
    828.80x = 1,240.80 × 742.40
  4. Step 4: Simplify right side
    828.80x = 921,169.92
  5. Step 5: Solve for x
    x = 921,169.92/828.80
  6. Step 6: Final answer
    x = 1,111.45

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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.