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Finding the Fourth Proportional to 986.78, 1,478.75 and 724.72

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Solution

The fourth proportional to 986.78, 1,478.75 and 724.72 is: 1,086.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    986.78 : 1,478.75 = 724.72 : x
  2. Step 2: Convert to fraction form
    986.78/1,478.75 = 724.72/x
  3. Step 3: Cross multiply
    986.78x = 1,478.75 × 724.72
  4. Step 4: Simplify right side
    986.78x = 1,071,675.10
  5. Step 5: Solve for x
    x = 1,071,675.10/986.78
  6. Step 6: Final answer
    x = 1,086.04

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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.