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Finding the Fourth Proportional to 156.40, 215.78 and 90.88

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Solution

The fourth proportional to 156.40, 215.78 and 90.88 is: 125.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.40 : 215.78 = 90.88 : x
  2. Step 2: Convert to fraction form
    156.40/215.78 = 90.88/x
  3. Step 3: Cross multiply
    156.40x = 215.78 × 90.88
  4. Step 4: Simplify right side
    156.40x = 19,610.09
  5. Step 5: Solve for x
    x = 19,610.09/156.40
  6. Step 6: Final answer
    x = 125.38

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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.