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Finding the Fourth Proportional to 287.81, 431.78 and 105.21

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Solution

The fourth proportional to 287.81, 431.78 and 105.21 is: 157.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.81 : 431.78 = 105.21 : x
  2. Step 2: Convert to fraction form
    287.81/431.78 = 105.21/x
  3. Step 3: Cross multiply
    287.81x = 431.78 × 105.21
  4. Step 4: Simplify right side
    287.81x = 45,427.57
  5. Step 5: Solve for x
    x = 45,427.57/287.81
  6. Step 6: Final answer
    x = 157.84

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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.