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Finding the Fourth Proportional to 28.16, 42.30 and 21.40

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Solution

The fourth proportional to 28.16, 42.30 and 21.40 is: 32.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.16 : 42.30 = 21.40 : x
  2. Step 2: Convert to fraction form
    28.16/42.30 = 21.40/x
  3. Step 3: Cross multiply
    28.16x = 42.30 × 21.40
  4. Step 4: Simplify right side
    28.16x = 905.22
  5. Step 5: Solve for x
    x = 905.22/28.16
  6. Step 6: Final answer
    x = 32.15

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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.