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Finding the Fourth Proportional to 127.20, 190.80 and 99.78

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Solution

The fourth proportional to 127.20, 190.80 and 99.78 is: 149.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    127.20 : 190.80 = 99.78 : x
  2. Step 2: Convert to fraction form
    127.20/190.80 = 99.78/x
  3. Step 3: Cross multiply
    127.20x = 190.80 × 99.78
  4. Step 4: Simplify right side
    127.20x = 19,038.02
  5. Step 5: Solve for x
    x = 19,038.02/127.20
  6. Step 6: Final answer
    x = 149.67

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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.