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Finding the Fourth Proportional to 871.80, 1,307.72 and 821.08

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Solution

The fourth proportional to 871.80, 1,307.72 and 821.08 is: 1,231.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    871.80 : 1,307.72 = 821.08 : x
  2. Step 2: Convert to fraction form
    871.80/1,307.72 = 821.08/x
  3. Step 3: Cross multiply
    871.80x = 1,307.72 × 821.08
  4. Step 4: Simplify right side
    871.80x = 1,073,742.74
  5. Step 5: Solve for x
    x = 1,073,742.74/871.80
  6. Step 6: Final answer
    x = 1,231.64

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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.