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Finding the Fourth Proportional to 918.86, 1,268.13 and 639.02

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Solution

The fourth proportional to 918.86, 1,268.13 and 639.02 is: 881.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.86 : 1,268.13 = 639.02 : x
  2. Step 2: Convert to fraction form
    918.86/1,268.13 = 639.02/x
  3. Step 3: Cross multiply
    918.86x = 1,268.13 × 639.02
  4. Step 4: Simplify right side
    918.86x = 810,360.43
  5. Step 5: Solve for x
    x = 810,360.43/918.86
  6. Step 6: Final answer
    x = 881.92

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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.