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Finding the Fourth Proportional to 320.40, 480.30 and 128.16

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Solution

The fourth proportional to 320.40, 480.30 and 128.16 is: 192.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    320.40 : 480.30 = 128.16 : x
  2. Step 2: Convert to fraction form
    320.40/480.30 = 128.16/x
  3. Step 3: Cross multiply
    320.40x = 480.30 × 128.16
  4. Step 4: Simplify right side
    320.40x = 61,555.25
  5. Step 5: Solve for x
    x = 61,555.25/320.40
  6. Step 6: Final answer
    x = 192.12

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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.