Home / 991.81-1,368.52-642.30

Finding the Fourth Proportional to 991.81, 1,368.52 and 642.30

Calculator

Solution

The fourth proportional to 991.81, 1,368.52 and 642.30 is: 886.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.81 : 1,368.52 = 642.30 : x
  2. Step 2: Convert to fraction form
    991.81/1,368.52 = 642.30/x
  3. Step 3: Cross multiply
    991.81x = 1,368.52 × 642.30
  4. Step 4: Simplify right side
    991.81x = 878,990.34
  5. Step 5: Solve for x
    x = 878,990.34/991.81
  6. Step 6: Final answer
    x = 886.25

Related Problems

Find fourth proportional to 495.91, 684.26 and 321.15
Half scale
Find fourth proportional to 1,983.62, 2,737.03 and 1,284.59
Double scale
Find fourth proportional to 992.81, 1,369.89 and 643.30
Similar ratio
Find fourth proportional to 1,487.72, 2,052.77 and 963.44
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.