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Finding the Fourth Proportional to 1,991.99, 2,987.69 and 821.64

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Solution

The fourth proportional to 1,991.99, 2,987.69 and 821.64 is: 1,232.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,991.99 : 2,987.69 = 821.64 : x
  2. Step 2: Convert to fraction form
    1,991.99/2,987.69 = 821.64/x
  3. Step 3: Cross multiply
    1,991.99x = 2,987.69 × 821.64
  4. Step 4: Simplify right side
    1,991.99x = 2,454,812.71
  5. Step 5: Solve for x
    x = 2,454,812.71/1,991.99
  6. Step 6: Final answer
    x = 1,232.34

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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.