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Finding the Fourth Proportional to 1,272.50, 1,908.12 and 811.20

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Solution

The fourth proportional to 1,272.50, 1,908.12 and 811.20 is: 1,216.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,272.50 : 1,908.12 = 811.20 : x
  2. Step 2: Convert to fraction form
    1,272.50/1,908.12 = 811.20/x
  3. Step 3: Cross multiply
    1,272.50x = 1,908.12 × 811.20
  4. Step 4: Simplify right side
    1,272.50x = 1,547,872.58
  5. Step 5: Solve for x
    x = 1,547,872.58/1,272.50
  6. Step 6: Final answer
    x = 1,216.40

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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.