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Finding the Fourth Proportional to 156.34, 215.76 and 86.40

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Solution

The fourth proportional to 156.34, 215.76 and 86.40 is: 119.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.34 : 215.76 = 86.40 : x
  2. Step 2: Convert to fraction form
    156.34/215.76 = 86.40/x
  3. Step 3: Cross multiply
    156.34x = 215.76 × 86.40
  4. Step 4: Simplify right side
    156.34x = 18,642.10
  5. Step 5: Solve for x
    x = 18,642.10/156.34
  6. Step 6: Final answer
    x = 119.24

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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.