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Finding the Fourth Proportional to 979.40, 1,351.64 and 913.80

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Solution

The fourth proportional to 979.40, 1,351.64 and 913.80 is: 1,261.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.40 : 1,351.64 = 913.80 : x
  2. Step 2: Convert to fraction form
    979.40/1,351.64 = 913.80/x
  3. Step 3: Cross multiply
    979.40x = 1,351.64 × 913.80
  4. Step 4: Simplify right side
    979.40x = 1,235,128.63
  5. Step 5: Solve for x
    x = 1,235,128.63/979.40
  6. Step 6: Final answer
    x = 1,261.11

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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.