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Finding the Fourth Proportional to 128.42, 177.18 and 89.63

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Solution

The fourth proportional to 128.42, 177.18 and 89.63 is: 123.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.42 : 177.18 = 89.63 : x
  2. Step 2: Convert to fraction form
    128.42/177.18 = 89.63/x
  3. Step 3: Cross multiply
    128.42x = 177.18 × 89.63
  4. Step 4: Simplify right side
    128.42x = 15,880.64
  5. Step 5: Solve for x
    x = 15,880.64/128.42
  6. Step 6: Final answer
    x = 123.66

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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.