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Finding the Fourth Proportional to 985.28, 1,479.20 and 779.20

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Solution

The fourth proportional to 985.28, 1,479.20 and 779.20 is: 1,169.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.28 : 1,479.20 = 779.20 : x
  2. Step 2: Convert to fraction form
    985.28/1,479.20 = 779.20/x
  3. Step 3: Cross multiply
    985.28x = 1,479.20 × 779.20
  4. Step 4: Simplify right side
    985.28x = 1,152,592.64
  5. Step 5: Solve for x
    x = 1,152,592.64/985.28
  6. Step 6: Final answer
    x = 1,169.81

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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.