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Finding the Fourth Proportional to 990.80, 1,368.40 and 660.74

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Solution

The fourth proportional to 990.80, 1,368.40 and 660.74 is: 912.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.80 : 1,368.40 = 660.74 : x
  2. Step 2: Convert to fraction form
    990.80/1,368.40 = 660.74/x
  3. Step 3: Cross multiply
    990.80x = 1,368.40 × 660.74
  4. Step 4: Simplify right side
    990.80x = 904,156.62
  5. Step 5: Solve for x
    x = 904,156.62/990.80
  6. Step 6: Final answer
    x = 912.55

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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.