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Finding the Fourth Proportional to 105.21, 157.86 and 91.40

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Solution

The fourth proportional to 105.21, 157.86 and 91.40 is: 137.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.21 : 157.86 = 91.40 : x
  2. Step 2: Convert to fraction form
    105.21/157.86 = 91.40/x
  3. Step 3: Cross multiply
    105.21x = 157.86 × 91.40
  4. Step 4: Simplify right side
    105.21x = 14,427.61
  5. Step 5: Solve for x
    x = 14,427.61/105.21
  6. Step 6: Final answer
    x = 137.13

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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.