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Finding the Fourth Proportional to 111.45, 153.78 and 64.21

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Solution

The fourth proportional to 111.45, 153.78 and 64.21 is: 88.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.45 : 153.78 = 64.21 : x
  2. Step 2: Convert to fraction form
    111.45/153.78 = 64.21/x
  3. Step 3: Cross multiply
    111.45x = 153.78 × 64.21
  4. Step 4: Simplify right side
    111.45x = 9,873.78
  5. Step 5: Solve for x
    x = 9,873.78/111.45
  6. Step 6: Final answer
    x = 88.59

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.