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Finding the Fourth Proportional to 64.80, 89.40 and 39.56

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Solution

The fourth proportional to 64.80, 89.40 and 39.56 is: 54.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.80 : 89.40 = 39.56 : x
  2. Step 2: Convert to fraction form
    64.80/89.40 = 39.56/x
  3. Step 3: Cross multiply
    64.80x = 89.40 × 39.56
  4. Step 4: Simplify right side
    64.80x = 3,536.22
  5. Step 5: Solve for x
    x = 3,536.22/64.80
  6. Step 6: Final answer
    x = 54.57

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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.