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Finding the Fourth Proportional to 1,209, 1,667.79 and 711.60

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Solution

The fourth proportional to 1,209, 1,667.79 and 711.60 is: 981.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209 : 1,667.79 = 711.60 : x
  2. Step 2: Convert to fraction form
    1,209/1,667.79 = 711.60/x
  3. Step 3: Cross multiply
    1,209x = 1,667.79 × 711.60
  4. Step 4: Simplify right side
    1,209x = 1,186,799.36
  5. Step 5: Solve for x
    x = 1,186,799.36/1,209
  6. Step 6: Final answer
    x = 981.64

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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.