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Finding the Fourth Proportional to 1,287.21, 1,776.35 and 697.75

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Solution

The fourth proportional to 1,287.21, 1,776.35 and 697.75 is: 962.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.21 : 1,776.35 = 697.75 : x
  2. Step 2: Convert to fraction form
    1,287.21/1,776.35 = 697.75/x
  3. Step 3: Cross multiply
    1,287.21x = 1,776.35 × 697.75
  4. Step 4: Simplify right side
    1,287.21x = 1,239,440.28
  5. Step 5: Solve for x
    x = 1,239,440.28/1,287.21
  6. Step 6: Final answer
    x = 962.89

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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.