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Finding the Fourth Proportional to 72.18, 99.72 and 64.16

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Solution

The fourth proportional to 72.18, 99.72 and 64.16 is: 88.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.18 : 99.72 = 64.16 : x
  2. Step 2: Convert to fraction form
    72.18/99.72 = 64.16/x
  3. Step 3: Cross multiply
    72.18x = 99.72 × 64.16
  4. Step 4: Simplify right side
    72.18x = 6,398.04
  5. Step 5: Solve for x
    x = 6,398.04/72.18
  6. Step 6: Final answer
    x = 88.64

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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.