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Finding the Fourth Proportional to 919.82, 1,269.10 and 639.74

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Solution

The fourth proportional to 919.82, 1,269.10 and 639.74 is: 882.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.82 : 1,269.10 = 639.74 : x
  2. Step 2: Convert to fraction form
    919.82/1,269.10 = 639.74/x
  3. Step 3: Cross multiply
    919.82x = 1,269.10 × 639.74
  4. Step 4: Simplify right side
    919.82x = 811,894.03
  5. Step 5: Solve for x
    x = 811,894.03/919.82
  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.