Home / 718.40-991.20-438.60

Finding the Fourth Proportional to 718.40, 991.20 and 438.60

Calculator

Solution

The fourth proportional to 718.40, 991.20 and 438.60 is: 605.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.40 : 991.20 = 438.60 : x
  2. Step 2: Convert to fraction form
    718.40/991.20 = 438.60/x
  3. Step 3: Cross multiply
    718.40x = 991.20 × 438.60
  4. Step 4: Simplify right side
    718.40x = 434,740.32
  5. Step 5: Solve for x
    x = 434,740.32/718.40
  6. Step 6: Final answer
    x = 605.15

Related Problems

Find fourth proportional to 359.20, 495.60 and 219.30
Half scale
Find fourth proportional to 1,436.79, 1,982.40 and 877.20
Double scale
Find fourth proportional to 719.40, 992.58 and 439.60
Similar ratio
Find fourth proportional to 1,077.59, 1,486.80 and 657.90
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.