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Finding the Fourth Proportional to 1,981.80, 2,970.65 and 811.31

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Solution

The fourth proportional to 1,981.80, 2,970.65 and 811.31 is: 1,216.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,981.80 : 2,970.65 = 811.31 : x
  2. Step 2: Convert to fraction form
    1,981.80/2,970.65 = 811.31/x
  3. Step 3: Cross multiply
    1,981.80x = 2,970.65 × 811.31
  4. Step 4: Simplify right side
    1,981.80x = 2,410,099.14
  5. Step 5: Solve for x
    x = 2,410,099.14/1,981.80
  6. Step 6: Final answer
    x = 1,216.12

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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.