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Finding the Fourth Proportional to 991.20, 1,485.46 and 772.09

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Solution

The fourth proportional to 991.20, 1,485.46 and 772.09 is: 1,157.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.20 : 1,485.46 = 772.09 : x
  2. Step 2: Convert to fraction form
    991.20/1,485.46 = 772.09/x
  3. Step 3: Cross multiply
    991.20x = 1,485.46 × 772.09
  4. Step 4: Simplify right side
    991.20x = 1,146,908.81
  5. Step 5: Solve for x
    x = 1,146,908.81/991.20
  6. Step 6: Final answer
    x = 1,157.09

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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.