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Finding the Fourth Proportional to 1,311.08, 1,964.66 and 661

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Solution

The fourth proportional to 1,311.08, 1,964.66 and 661 is: 990.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.08 : 1,964.66 = 661 : x
  2. Step 2: Convert to fraction form
    1,311.08/1,964.66 = 661/x
  3. Step 3: Cross multiply
    1,311.08x = 1,964.66 × 661
  4. Step 4: Simplify right side
    1,311.08x = 1,298,640.26
  5. Step 5: Solve for x
    x = 1,298,640.26/1,311.08
  6. Step 6: Final answer
    x = 990.51

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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.