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Finding the Fourth Proportional to 156.30, 215.70 and 90.81

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Solution

The fourth proportional to 156.30, 215.70 and 90.81 is: 125.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.30 : 215.70 = 90.81 : x
  2. Step 2: Convert to fraction form
    156.30/215.70 = 90.81/x
  3. Step 3: Cross multiply
    156.30x = 215.70 × 90.81
  4. Step 4: Simplify right side
    156.30x = 19,587.72
  5. Step 5: Solve for x
    x = 19,587.72/156.30
  6. Step 6: Final answer
    x = 125.32

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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.