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Finding the Fourth Proportional to 1,215.91, 1,678.20 and 718.53

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Solution

The fourth proportional to 1,215.91, 1,678.20 and 718.53 is: 991.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,215.91 : 1,678.20 = 718.53 : x
  2. Step 2: Convert to fraction form
    1,215.91/1,678.20 = 718.53/x
  3. Step 3: Cross multiply
    1,215.91x = 1,678.20 × 718.53
  4. Step 4: Simplify right side
    1,215.91x = 1,205,825.06
  5. Step 5: Solve for x
    x = 1,205,825.06/1,215.91
  6. Step 6: Final answer
    x = 991.71

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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.