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Finding the Fourth Proportional to 1,187.91, 1,782.62 and 640.47

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Solution

The fourth proportional to 1,187.91, 1,782.62 and 640.47 is: 961.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.91 : 1,782.62 = 640.47 : x
  2. Step 2: Convert to fraction form
    1,187.91/1,782.62 = 640.47/x
  3. Step 3: Cross multiply
    1,187.91x = 1,782.62 × 640.47
  4. Step 4: Simplify right side
    1,187.91x = 1,141,714.63
  5. Step 5: Solve for x
    x = 1,141,714.63/1,187.91
  6. Step 6: Final answer
    x = 961.12

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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.