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Finding the Fourth Proportional to 825.30, 1,139.92 and 639.40

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Solution

The fourth proportional to 825.30, 1,139.92 and 639.40 is: 883.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    825.30 : 1,139.92 = 639.40 : x
  2. Step 2: Convert to fraction form
    825.30/1,139.92 = 639.40/x
  3. Step 3: Cross multiply
    825.30x = 1,139.92 × 639.40
  4. Step 4: Simplify right side
    825.30x = 728,864.85
  5. Step 5: Solve for x
    x = 728,864.85/825.30
  6. Step 6: Final answer
    x = 883.15

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1.5x scale

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.