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Finding the Fourth Proportional to 1,074, 1,611 and 390

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Solution

The fourth proportional to 1,074, 1,611 and 390 is: 585

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,074 : 1,611 = 390 : x
  2. Step 2: Convert to fraction form
    1,074/1,611 = 390/x
  3. Step 3: Cross multiply
    1,074x = 1,611 × 390
  4. Step 4: Simplify right side
    1,074x = 628,290
  5. Step 5: Solve for x
    x = 628,290/1,074
  6. Step 6: Final answer
    x = 585

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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.