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Finding the Fourth Proportional to 1,290.72, 1,935.36 and 640.56

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Solution

The fourth proportional to 1,290.72, 1,935.36 and 640.56 is: 960.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.72 : 1,935.36 = 640.56 : x
  2. Step 2: Convert to fraction form
    1,290.72/1,935.36 = 640.56/x
  3. Step 3: Cross multiply
    1,290.72x = 1,935.36 × 640.56
  4. Step 4: Simplify right side
    1,290.72x = 1,239,714.20
  5. Step 5: Solve for x
    x = 1,239,714.20/1,290.72
  6. Step 6: Final answer
    x = 960.48

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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.