A council uses a computational model to predict when a road junction should show a red signal to prevent congestion. At the start of the model there are 12 ...

A council uses a computational model to predict when a road junction should show a red signal to prevent congestion. At the start of the model there are 12 cars waiting. During each minute, sensors provide the number of cars that entered the queue and the number that left it. The model updates the value of cars. If more than 20 cars are waiting, it sets signal to RED; otherwise it sets signal to GREEN.

cars ← 12
FOR minute ← 1 TO 4
    INPUT entered, left
    cars ← cars + entered - left
    IF cars > 20 THEN
        signal ← "RED"
    ELSE
        signal ← "GREEN"
    ENDIF
    OUTPUT cars, signal
NEXT minute

The sensor data are shown below. A separate sensor records 00011000 as an eight-bit binary car count. The model is an approximation: it does not include factors such as weather, pedestrians or drivers ignoring signals.

(a) State the two values input by the sensors on each iteration. [2]
(b) Identify the line or structure that repeats the model for each minute. [1]
(c) Complete the trace table. [4]
(d) Complete the data types: cars is an __________; signal is a __________. [2]
(e) Convert 00011000 from binary to denary. [1]
(f) Give one factor, other than those stated, that could make this model less accurate. [1]
(g) Explain why the council should validate sensor input values before using them in the model. [2]
(h) State one value output by the model during each iteration. [1]