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Finding the Fourth Proportional to 978.12, 1,348.92 and 812.88

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Solution

The fourth proportional to 978.12, 1,348.92 and 812.88 is: 1,121.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.12 : 1,348.92 = 812.88 : x
  2. Step 2: Convert to fraction form
    978.12/1,348.92 = 812.88/x
  3. Step 3: Cross multiply
    978.12x = 1,348.92 × 812.88
  4. Step 4: Simplify right side
    978.12x = 1,096,510.09
  5. Step 5: Solve for x
    x = 1,096,510.09/978.12
  6. Step 6: Final answer
    x = 1,121.04

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.