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Finding the Fourth Proportional to 928.16, 1,391.68 and 639.28

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Solution

The fourth proportional to 928.16, 1,391.68 and 639.28 is: 958.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    928.16 : 1,391.68 = 639.28 : x
  2. Step 2: Convert to fraction form
    928.16/1,391.68 = 639.28/x
  3. Step 3: Cross multiply
    928.16x = 1,391.68 × 639.28
  4. Step 4: Simplify right side
    928.16x = 889,673.19
  5. Step 5: Solve for x
    x = 889,673.19/928.16
  6. Step 6: Final answer
    x = 958.53

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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.