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Finding the Fourth Proportional to 157.80, 236.78 and 85.68

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Solution

The fourth proportional to 157.80, 236.78 and 85.68 is: 128.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    157.80 : 236.78 = 85.68 : x
  2. Step 2: Convert to fraction form
    157.80/236.78 = 85.68/x
  3. Step 3: Cross multiply
    157.80x = 236.78 × 85.68
  4. Step 4: Simplify right side
    157.80x = 20,287.31
  5. Step 5: Solve for x
    x = 20,287.31/157.80
  6. Step 6: Final answer
    x = 128.56

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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.