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Finding the Fourth Proportional to 786.40, 1,085.24 and 491.84

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Solution

The fourth proportional to 786.40, 1,085.24 and 491.84 is: 678.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.40 : 1,085.24 = 491.84 : x
  2. Step 2: Convert to fraction form
    786.40/1,085.24 = 491.84/x
  3. Step 3: Cross multiply
    786.40x = 1,085.24 × 491.84
  4. Step 4: Simplify right side
    786.40x = 533,764.44
  5. Step 5: Solve for x
    x = 533,764.44/786.40
  6. Step 6: Final answer
    x = 678.74

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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.