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Finding the Fourth Proportional to 1,321.80, 1,982.72 and 909.71

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Solution

The fourth proportional to 1,321.80, 1,982.72 and 909.71 is: 1,364.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,321.80 : 1,982.72 = 909.71 : x
  2. Step 2: Convert to fraction form
    1,321.80/1,982.72 = 909.71/x
  3. Step 3: Cross multiply
    1,321.80x = 1,982.72 × 909.71
  4. Step 4: Simplify right side
    1,321.80x = 1,803,685.75
  5. Step 5: Solve for x
    x = 1,803,685.75/1,321.80
  6. Step 6: Final answer
    x = 1,364.57

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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.