Home / 869.60-1,200-636.80

Finding the Fourth Proportional to 869.60, 1,200 and 636.80

Calculator

Solution

The fourth proportional to 869.60, 1,200 and 636.80 is: 878.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    869.60 : 1,200 = 636.80 : x
  2. Step 2: Convert to fraction form
    869.60/1,200 = 636.80/x
  3. Step 3: Cross multiply
    869.60x = 1,200 × 636.80
  4. Step 4: Simplify right side
    869.60x = 764,160
  5. Step 5: Solve for x
    x = 764,160/869.60
  6. Step 6: Final answer
    x = 878.75

Related Problems

Find fourth proportional to 434.80, 600 and 318.40
Half scale
Find fourth proportional to 1,739.20, 2,400 and 1,273.60
Double scale
Find fourth proportional to 870.60, 1,201.38 and 637.80
Similar ratio
Find fourth proportional to 1,304.40, 1,800 and 955.20
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.