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Finding the Fourth Proportional to 305.15, 421.12 and 172.40

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Solution

The fourth proportional to 305.15, 421.12 and 172.40 is: 237.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    305.15 : 421.12 = 172.40 : x
  2. Step 2: Convert to fraction form
    305.15/421.12 = 172.40/x
  3. Step 3: Cross multiply
    305.15x = 421.12 × 172.40
  4. Step 4: Simplify right side
    305.15x = 72,602.03
  5. Step 5: Solve for x
    x = 72,602.03/305.15
  6. Step 6: Final answer
    x = 237.92

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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.