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Finding the Fourth Proportional to 1,987.09, 2,980.65 and 672.31

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Solution

The fourth proportional to 1,987.09, 2,980.65 and 672.31 is: 1,008.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.09 : 2,980.65 = 672.31 : x
  2. Step 2: Convert to fraction form
    1,987.09/2,980.65 = 672.31/x
  3. Step 3: Cross multiply
    1,987.09x = 2,980.65 × 672.31
  4. Step 4: Simplify right side
    1,987.09x = 2,003,920.80
  5. Step 5: Solve for x
    x = 2,003,920.80/1,987.09
  6. Step 6: Final answer
    x = 1,008.47

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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.