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Finding the Fourth Proportional to 1,139, 1,571.70 and 641.48

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Solution

The fourth proportional to 1,139, 1,571.70 and 641.48 is: 885.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139 : 1,571.70 = 641.48 : x
  2. Step 2: Convert to fraction form
    1,139/1,571.70 = 641.48/x
  3. Step 3: Cross multiply
    1,139x = 1,571.70 × 641.48
  4. Step 4: Simplify right side
    1,139x = 1,008,214.12
  5. Step 5: Solve for x
    x = 1,008,214.12/1,139
  6. Step 6: Final answer
    x = 885.17

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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.