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Finding the Fourth Proportional to 1,390.80, 2,086.64 and 513.44

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Solution

The fourth proportional to 1,390.80, 2,086.64 and 513.44 is: 770.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.80 : 2,086.64 = 513.44 : x
  2. Step 2: Convert to fraction form
    1,390.80/2,086.64 = 513.44/x
  3. Step 3: Cross multiply
    1,390.80x = 2,086.64 × 513.44
  4. Step 4: Simplify right side
    1,390.80x = 1,071,364.44
  5. Step 5: Solve for x
    x = 1,071,364.44/1,390.80
  6. Step 6: Final answer
    x = 770.32

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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.