C

9000007208

Level: 
C
Paul's home is 6km from the school. At the time t=0 Paul starts to walk from his home to the school along a straight street at a constant velocity 5km/h. Find the function which describes Paul's remaining distance to the school as a function of time.
s=6−5t
s=5t−6
s=5t
s=5t+6

9000007809

Level: 
C
The price of a goods in a shop is $15 per item. The Internet price in an e-shop is cheaper by $2 per item. The shipping cost of the e-shop is $125. What is the minimal number of items, which makes the total cost for a transaction smaller in the e-shop?
63
9
62
125
126

9000007810

Level: 
C
A fuel tank in a car has the capacity 40 litres. The current volume of the fuel in the fuel tank is 6 litres. The speed of fuelling is 1 litre of gasoline each 3 seconds. Find the function which describes the volume of the gasoline in the fuel tank (in litres) as a function of time (in seconds).
V=13t+6, t∈[0;102]
V=3t+6, t∈[0;102]
V=3t+6, t∈[0;40]
V=3t+6, t∈R0+
V=13t+6, t∈[0;40]

9000007210

Level: 
C
Jane has to reach the opposite shore of a lake. She has three possibilities how to cross. She can use her own boat, start immediately and sail at the velocity 4km/h. Another option is to wait for her friend, Peter, with a faster boat. Peter's boat is capable to sail at the velocity 10km/h. However, his boat will be available in 1.5 hours from now. The last option is to use the regular passenger transportation line which will departure in 2.25 hours from now and sails at the speed 20km/h. Find the interval of distances to the opposite shore for which the fastest option is to use Peter's boat.
between 10 and 15 kilometers
up to 10 kilometers
between 15 and 20 kilometers
larger that 20 kilometers