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Finding the Fourth Proportional to 1,328.80, 1,991.68 and 678.08

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Solution

The fourth proportional to 1,328.80, 1,991.68 and 678.08 is: 1,016.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,328.80 : 1,991.68 = 678.08 : x
  2. Step 2: Convert to fraction form
    1,328.80/1,991.68 = 678.08/x
  3. Step 3: Cross multiply
    1,328.80x = 1,991.68 × 678.08
  4. Step 4: Simplify right side
    1,328.80x = 1,350,518.37
  5. Step 5: Solve for x
    x = 1,350,518.37/1,328.80
  6. Step 6: Final answer
    x = 1,016.34

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.