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Finding the Fourth Proportional to 1,143.72, 1,578.36 and 639.61

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Solution

The fourth proportional to 1,143.72, 1,578.36 and 639.61 is: 882.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,143.72 : 1,578.36 = 639.61 : x
  2. Step 2: Convert to fraction form
    1,143.72/1,578.36 = 639.61/x
  3. Step 3: Cross multiply
    1,143.72x = 1,578.36 × 639.61
  4. Step 4: Simplify right side
    1,143.72x = 1,009,526.95
  5. Step 5: Solve for x
    x = 1,009,526.95/1,143.72
  6. Step 6: Final answer
    x = 882.67

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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.