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Finding the Fourth Proportional to 428.98, 643.48 and 155

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Solution

The fourth proportional to 428.98, 643.48 and 155 is: 232.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.98 : 643.48 = 155 : x
  2. Step 2: Convert to fraction form
    428.98/643.48 = 155/x
  3. Step 3: Cross multiply
    428.98x = 643.48 × 155
  4. Step 4: Simplify right side
    428.98x = 99,739.40
  5. Step 5: Solve for x
    x = 99,739.40/428.98
  6. Step 6: Final answer
    x = 232.50

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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.