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Finding the Fourth Proportional to 891.69, 1,231.19 and 643.56

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Solution

The fourth proportional to 891.69, 1,231.19 and 643.56 is: 888.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.69 : 1,231.19 = 643.56 : x
  2. Step 2: Convert to fraction form
    891.69/1,231.19 = 643.56/x
  3. Step 3: Cross multiply
    891.69x = 1,231.19 × 643.56
  4. Step 4: Simplify right side
    891.69x = 792,341.42
  5. Step 5: Solve for x
    x = 792,341.42/891.69
  6. Step 6: Final answer
    x = 888.58

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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.