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Finding the Fourth Proportional to 1,391.80, 1,921.09 and 802.75

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Solution

The fourth proportional to 1,391.80, 1,921.09 and 802.75 is: 1,108.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.80 : 1,921.09 = 802.75 : x
  2. Step 2: Convert to fraction form
    1,391.80/1,921.09 = 802.75/x
  3. Step 3: Cross multiply
    1,391.80x = 1,921.09 × 802.75
  4. Step 4: Simplify right side
    1,391.80x = 1,542,155.00
  5. Step 5: Solve for x
    x = 1,542,155.00/1,391.80
  6. Step 6: Final answer
    x = 1,108.03

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1.5x scale

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.