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Finding the Fourth Proportional to 428.93, 643.48 and 172.45

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Solution

The fourth proportional to 428.93, 643.48 and 172.45 is: 258.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.93 : 643.48 = 172.45 : x
  2. Step 2: Convert to fraction form
    428.93/643.48 = 172.45/x
  3. Step 3: Cross multiply
    428.93x = 643.48 × 172.45
  4. Step 4: Simplify right side
    428.93x = 110,967.26
  5. Step 5: Solve for x
    x = 110,967.26/428.93
  6. Step 6: Final answer
    x = 258.71

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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.