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Finding the Fourth Proportional to 825.40, 1,238.10 and 643.15

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Solution

The fourth proportional to 825.40, 1,238.10 and 643.15 is: 964.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    825.40 : 1,238.10 = 643.15 : x
  2. Step 2: Convert to fraction form
    825.40/1,238.10 = 643.15/x
  3. Step 3: Cross multiply
    825.40x = 1,238.10 × 643.15
  4. Step 4: Simplify right side
    825.40x = 796,284.02
  5. Step 5: Solve for x
    x = 796,284.02/825.40
  6. Step 6: Final answer
    x = 964.73

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Double scale
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Similar ratio
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.