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Finding the Fourth Proportional to 859.40, 1,187.70 and 639.08

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Solution

The fourth proportional to 859.40, 1,187.70 and 639.08 is: 883.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.40 : 1,187.70 = 639.08 : x
  2. Step 2: Convert to fraction form
    859.40/1,187.70 = 639.08/x
  3. Step 3: Cross multiply
    859.40x = 1,187.70 × 639.08
  4. Step 4: Simplify right side
    859.40x = 759,035.32
  5. Step 5: Solve for x
    x = 759,035.32/859.40
  6. Step 6: Final answer
    x = 883.22

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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.