Home / 628.80-878.40-628.80

Finding the Fourth Proportional to 628.80, 878.40 and 628.80

Calculator

Solution

The fourth proportional to 628.80, 878.40 and 628.80 is: 878.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    628.80 : 878.40 = 628.80 : x
  2. Step 2: Convert to fraction form
    628.80/878.40 = 628.80/x
  3. Step 3: Cross multiply
    628.80x = 878.40 × 628.80
  4. Step 4: Simplify right side
    628.80x = 552,337.92
  5. Step 5: Solve for x
    x = 552,337.92/628.80
  6. Step 6: Final answer
    x = 878.40

Related Problems

Find fourth proportional to 314.40, 439.20 and 314.40
Half scale
Find fourth proportional to 1,257.60, 1,756.80 and 1,257.60
Double scale
Find fourth proportional to 629.80, 879.80 and 629.80
Similar ratio
Find fourth proportional to 943.20, 1,317.60 and 943.20
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.40) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.