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Finding the Fourth Proportional to 1,987.34, 2,981.61 and 689.18

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Solution

The fourth proportional to 1,987.34, 2,981.61 and 689.18 is: 1,033.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.34 : 2,981.61 = 689.18 : x
  2. Step 2: Convert to fraction form
    1,987.34/2,981.61 = 689.18/x
  3. Step 3: Cross multiply
    1,987.34x = 2,981.61 × 689.18
  4. Step 4: Simplify right side
    1,987.34x = 2,054,851.07
  5. Step 5: Solve for x
    x = 2,054,851.07/1,987.34
  6. Step 6: Final answer
    x = 1,033.97

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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.