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Finding the Fourth Proportional to 287.80, 431.35 and 143.21

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Solution

The fourth proportional to 287.80, 431.35 and 143.21 is: 214.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.80 : 431.35 = 143.21 : x
  2. Step 2: Convert to fraction form
    287.80/431.35 = 143.21/x
  3. Step 3: Cross multiply
    287.80x = 431.35 × 143.21
  4. Step 4: Simplify right side
    287.80x = 61,773.63
  5. Step 5: Solve for x
    x = 61,773.63/287.80
  6. Step 6: Final answer
    x = 214.64

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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.