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Finding the Fourth Proportional to 1,290.76, 1,782.10 and 991.46

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Solution

The fourth proportional to 1,290.76, 1,782.10 and 991.46 is: 1,368.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.76 : 1,782.10 = 991.46 : x
  2. Step 2: Convert to fraction form
    1,290.76/1,782.10 = 991.46/x
  3. Step 3: Cross multiply
    1,290.76x = 1,782.10 × 991.46
  4. Step 4: Simplify right side
    1,290.76x = 1,766,880.87
  5. Step 5: Solve for x
    x = 1,766,880.87/1,290.76
  6. Step 6: Final answer
    x = 1,368.87

Related Problems

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Double scale
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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.