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Finding the Fourth Proportional to 1,239.64, 1,710.81 and 715.78

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Solution

The fourth proportional to 1,239.64, 1,710.81 and 715.78 is: 987.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.64 : 1,710.81 = 715.78 : x
  2. Step 2: Convert to fraction form
    1,239.64/1,710.81 = 715.78/x
  3. Step 3: Cross multiply
    1,239.64x = 1,710.81 × 715.78
  4. Step 4: Simplify right side
    1,239.64x = 1,224,563.58
  5. Step 5: Solve for x
    x = 1,224,563.58/1,239.64
  6. Step 6: Final answer
    x = 987.84

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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.