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Finding the Fourth Proportional to 1,987.21, 2,980.84 and 688.38

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Solution

The fourth proportional to 1,987.21, 2,980.84 and 688.38 is: 1,032.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.21 : 2,980.84 = 688.38 : x
  2. Step 2: Convert to fraction form
    1,987.21/2,980.84 = 688.38/x
  3. Step 3: Cross multiply
    1,987.21x = 2,980.84 × 688.38
  4. Step 4: Simplify right side
    1,987.21x = 2,051,950.64
  5. Step 5: Solve for x
    x = 2,051,950.64/1,987.21
  6. Step 6: Final answer
    x = 1,032.58

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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.