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Finding the Fourth Proportional to 65, 89.70 and 42

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Solution

The fourth proportional to 65, 89.70 and 42 is: 57.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    65 : 89.70 = 42 : x
  2. Step 2: Convert to fraction form
    65/89.70 = 42/x
  3. Step 3: Cross multiply
    65x = 89.70 × 42
  4. Step 4: Simplify right side
    65x = 3,767.40
  5. Step 5: Solve for x
    x = 3,767.40/65
  6. Step 6: Final answer
    x = 57.96

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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.