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Finding the Fourth Proportional to 1,989.90, 2,985.12 and 691.02

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Solution

The fourth proportional to 1,989.90, 2,985.12 and 691.02 is: 1,036.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,989.90 : 2,985.12 = 691.02 : x
  2. Step 2: Convert to fraction form
    1,989.90/2,985.12 = 691.02/x
  3. Step 3: Cross multiply
    1,989.90x = 2,985.12 × 691.02
  4. Step 4: Simplify right side
    1,989.90x = 2,062,777.62
  5. Step 5: Solve for x
    x = 2,062,777.62/1,989.90
  6. Step 6: Final answer
    x = 1,036.62

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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.