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Finding the Fourth Proportional to 156.40, 215.84 and 86.45

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Solution

The fourth proportional to 156.40, 215.84 and 86.45 is: 119.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.40 : 215.84 = 86.45 : x
  2. Step 2: Convert to fraction form
    156.40/215.84 = 86.45/x
  3. Step 3: Cross multiply
    156.40x = 215.84 × 86.45
  4. Step 4: Simplify right side
    156.40x = 18,659.48
  5. Step 5: Solve for x
    x = 18,659.48/156.40
  6. Step 6: Final answer
    x = 119.31

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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.