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Finding the Fourth Proportional to 74.40, 102.72 and 64.80

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Solution

The fourth proportional to 74.40, 102.72 and 64.80 is: 89.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.40 : 102.72 = 64.80 : x
  2. Step 2: Convert to fraction form
    74.40/102.72 = 64.80/x
  3. Step 3: Cross multiply
    74.40x = 102.72 × 64.80
  4. Step 4: Simplify right side
    74.40x = 6,656.26
  5. Step 5: Solve for x
    x = 6,656.26/74.40
  6. Step 6: Final answer
    x = 89.47

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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.