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Finding the Fourth Proportional to 811.37, 1,215.66 and 639.14

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Solution

The fourth proportional to 811.37, 1,215.66 and 639.14 is: 957.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.37 : 1,215.66 = 639.14 : x
  2. Step 2: Convert to fraction form
    811.37/1,215.66 = 639.14/x
  3. Step 3: Cross multiply
    811.37x = 1,215.66 × 639.14
  4. Step 4: Simplify right side
    811.37x = 776,976.93
  5. Step 5: Solve for x
    x = 776,976.93/811.37
  6. Step 6: Final answer
    x = 957.61

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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.