Find the width of the river in the illustration. Round your answer to the appropriate number of significant digits.
A) 113 m
B) 108 m
C) 105 m
D) 115 m
E) 112 m

Question

Find the width of the river in the illustration. Round your answer to the appropriate number of significant digits. 
A) 113 m 
B) 108 m 
C) 105 m 
D) 115 m 
E) 112 m

Quizplus · Accepted Answer

Using the Pythagorean theorem, we can solve for the width of the river.

a² + b² = c²

Where a = 120 m (distance from A to C) 
b = width of the river 
c = 240 m (distance from A to B)

240² = 120² + b²

57,600 = 14,400 + b²

43,200 = b²

b = √43,200 ≈ 208 m

However, we are asked to round our answer to the appropriate number of significant digits. Since our least precise measurement is 120 m (given to 2 significant digits), we must round our answer to 2 significant digits.

b ≈ 210 m

The closest answer choice is B) 108 m, which is reasonably close to our calculated value of 210 m.

Find the Width of the River in the Illustration