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Finding the Fourth Proportional to 1,987.08, 2,980.62 and 688.55

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Solution

The fourth proportional to 1,987.08, 2,980.62 and 688.55 is: 1,032.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.08 : 2,980.62 = 688.55 : x
  2. Step 2: Convert to fraction form
    1,987.08/2,980.62 = 688.55/x
  3. Step 3: Cross multiply
    1,987.08x = 2,980.62 × 688.55
  4. Step 4: Simplify right side
    1,987.08x = 2,052,302.18
  5. Step 5: Solve for x
    x = 2,052,302.18/1,987.08
  6. Step 6: Final answer
    x = 1,032.82

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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.