NBT NBT Quantitative Literacy: Ratios, Proportions and Rates 3

Question 1

A school's learner-to-teacher ratio is 35:1. If there are 7 teachers, how many learners are there?

Accepted Answer

245

Answer

Learners = 35 × 7 = 245.

Question 2

A runner completes a 10 km race in 50 minutes. What is her average speed in km/h?

Accepted Answer

12 km/h

Answer

Speed = 10 ÷ (50/60) = 10 × (60/50) = 12 km/h.

Question 3

A model car is built at a scale of 1:24. The real car is 4.2 m long. How long is the model car in cm?

Accepted Answer

17.5 cm

Answer

4.2 m = 420 cm; model length = 420 ÷ 24 = 17.5 cm.

Question 4

A grocery store sells 1.5 litres of juice for R18 and 2 litres for R22. Which is the better value?

Accepted Answer

2-litre bottle

Answer

1.5 L: R18/1.5 = R12/L; 2 L: R22/2 = R11/L — the 2-litre bottle is cheaper per litre.

Question 5

If y is inversely proportional to x and y = 8 when x = 3, what is y when x = 12?

Accepted Answer

2

Answer

Constant k = 8 × 3 = 24; y = 24 ÷ 12 = 2.

(NBT) National Benchmark Test Practice Test