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Finding the Fourth Proportional to 1,328.20, 1,992.30 and 781.45

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Solution

The fourth proportional to 1,328.20, 1,992.30 and 781.45 is: 1,172.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,328.20 : 1,992.30 = 781.45 : x
  2. Step 2: Convert to fraction form
    1,328.20/1,992.30 = 781.45/x
  3. Step 3: Cross multiply
    1,328.20x = 1,992.30 × 781.45
  4. Step 4: Simplify right side
    1,328.20x = 1,556,882.84
  5. Step 5: Solve for x
    x = 1,556,882.84/1,328.20
  6. Step 6: Final answer
    x = 1,172.18

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1.5x scale

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.