Home / 823.80-1,139.76-720.60

Finding the Fourth Proportional to 823.80, 1,139.76 and 720.60

Calculator

Solution

The fourth proportional to 823.80, 1,139.76 and 720.60 is: 996.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    823.80 : 1,139.76 = 720.60 : x
  2. Step 2: Convert to fraction form
    823.80/1,139.76 = 720.60/x
  3. Step 3: Cross multiply
    823.80x = 1,139.76 × 720.60
  4. Step 4: Simplify right side
    823.80x = 821,311.06
  5. Step 5: Solve for x
    x = 821,311.06/823.80
  6. Step 6: Final answer
    x = 996.98

Related Problems

Find fourth proportional to 411.90, 569.88 and 360.30
Half scale
Find fourth proportional to 1,647.60, 2,279.52 and 1,441.20
Double scale
Find fourth proportional to 824.80, 1,141.14 and 721.60
Similar ratio
Find fourth proportional to 1,235.70, 1,709.64 and 1,080.90
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.