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Finding the Fourth Proportional to 921.08, 1,268.18 and 780.90

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Solution

The fourth proportional to 921.08, 1,268.18 and 780.90 is: 1,075.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.08 : 1,268.18 = 780.90 : x
  2. Step 2: Convert to fraction form
    921.08/1,268.18 = 780.90/x
  3. Step 3: Cross multiply
    921.08x = 1,268.18 × 780.90
  4. Step 4: Simplify right side
    921.08x = 990,321.76
  5. Step 5: Solve for x
    x = 990,321.76/921.08
  6. Step 6: Final answer
    x = 1,075.17

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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.