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Finding the Fourth Proportional to 811.89, 1,118.21 and 687.15

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Solution

The fourth proportional to 811.89, 1,118.21 and 687.15 is: 946.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.89 : 1,118.21 = 687.15 : x
  2. Step 2: Convert to fraction form
    811.89/1,118.21 = 687.15/x
  3. Step 3: Cross multiply
    811.89x = 1,118.21 × 687.15
  4. Step 4: Simplify right side
    811.89x = 768,374.57
  5. Step 5: Solve for x
    x = 768,374.57/811.89
  6. Step 6: Final answer
    x = 946.40

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Double scale
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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.