2005 CEMC Gauss (Grade 7) Problems/Problem 20

Problem

While driving at $80 km/h$ , Sally’s car passes a hydro pole every four seconds. Which of the following is closest to the distance between two neighbouring hydro poles?

$\text{(A)}\ 50 m \qquad \text{(B)}\ 60 m \qquad \text{(C)}\ 70 m \qquad \text{(D)}\ 80 m \qquad \text{(E)}\ 90 m$

Solution

Since Sally’s car travels $80 km/h$ , it travels $80,000 m$ in one hour. Since there are $60$ minutes in an hour, the car travels $\frac{1}{60}\times 80,000 m$ in one minute. Since there are $60$ seconds in a minute, the car travels $\frac{1}{60}\times \frac{1}{60}\times 80,000 m$ in one second. Therefore, in $4$ seconds, the car travels $4\times \frac{1}{60}\times \frac{1}{60}\times 80,000 = 88.89 m$ . Of the possible choices, this is closest to 90 m. Therefore, the answer is $E$ .

2005 CEMC Gauss (Grade 7) (Problems • Answer Key • Resources)
Preceded by Problem 19	Followed by Problem 21
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25
CEMC Gauss (Grade 7)

Page

Toolbox

Search

2005 CEMC Gauss (Grade 7) Problems/Problem 20

Problem

Solution

See Also