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Finding the Fourth Proportional to 1,990.34, 2,985.78 and 691.58

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Solution

The fourth proportional to 1,990.34, 2,985.78 and 691.58 is: 1,037.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,990.34 : 2,985.78 = 691.58 : x
  2. Step 2: Convert to fraction form
    1,990.34/2,985.78 = 691.58/x
  3. Step 3: Cross multiply
    1,990.34x = 2,985.78 × 691.58
  4. Step 4: Simplify right side
    1,990.34x = 2,064,905.73
  5. Step 5: Solve for x
    x = 2,064,905.73/1,990.34
  6. Step 6: Final answer
    x = 1,037.46

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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.