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Finding the Fourth Proportional to 918.95, 1,267.92 and 639.77

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Solution

The fourth proportional to 918.95, 1,267.92 and 639.77 is: 882.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.95 : 1,267.92 = 639.77 : x
  2. Step 2: Convert to fraction form
    918.95/1,267.92 = 639.77/x
  3. Step 3: Cross multiply
    918.95x = 1,267.92 × 639.77
  4. Step 4: Simplify right side
    918.95x = 811,170.84
  5. Step 5: Solve for x
    x = 811,170.84/918.95
  6. Step 6: Final answer
    x = 882.72

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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.