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Finding the Fourth Proportional to 1,688.72, 2,331 and 989.84

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Solution

The fourth proportional to 1,688.72, 2,331 and 989.84 is: 1,366.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,688.72 : 2,331 = 989.84 : x
  2. Step 2: Convert to fraction form
    1,688.72/2,331 = 989.84/x
  3. Step 3: Cross multiply
    1,688.72x = 2,331 × 989.84
  4. Step 4: Simplify right side
    1,688.72x = 2,307,317.04
  5. Step 5: Solve for x
    x = 2,307,317.04/1,688.72
  6. Step 6: Final answer
    x = 1,366.31

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.