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Finding the Fourth Proportional to 1,208.80, 1,668 and 711.40

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Solution

The fourth proportional to 1,208.80, 1,668 and 711.40 is: 981.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,208.80 : 1,668 = 711.40 : x
  2. Step 2: Convert to fraction form
    1,208.80/1,668 = 711.40/x
  3. Step 3: Cross multiply
    1,208.80x = 1,668 × 711.40
  4. Step 4: Simplify right side
    1,208.80x = 1,186,615.20
  5. Step 5: Solve for x
    x = 1,186,615.20/1,208.80
  6. Step 6: Final answer
    x = 981.65

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.