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Finding the Fourth Proportional to 1,320.20, 1,980.30 and 772.10

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Solution

The fourth proportional to 1,320.20, 1,980.30 and 772.10 is: 1,158.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.20 : 1,980.30 = 772.10 : x
  2. Step 2: Convert to fraction form
    1,320.20/1,980.30 = 772.10/x
  3. Step 3: Cross multiply
    1,320.20x = 1,980.30 × 772.10
  4. Step 4: Simplify right side
    1,320.20x = 1,528,989.63
  5. Step 5: Solve for x
    x = 1,528,989.63/1,320.20
  6. Step 6: Final answer
    x = 1,158.15

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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.