2.1 Algorithms

Question 1

algorithms

Answer 1

provide precise instructions needed to solve a problem

all computer programs are algorithms

a step-by-step procedure for solving a problem or carrying out a task

Question 2

uses for algorithms

Answer 2

often used to improve efficiency by removing the need for human input

e.g. automatic-pilot systems

Question 3

advantages of an algorithm

Answer 3

a computer following an algorithm can decide what to do far quicker than a human, which can be extremely valuable (e.g. when stock market trading)

Question 4

constructs of an algorithm

Answer 4

sequence
selection
iteration

Question 5

sequence

Answer 5

instructions need to be given in the correct order

instructions are read in a specific order

Question 6

selection

Answer 6

decisions are made and a course of action is chosen

Question 7

iteration

Answer 7

previous steps are repeated until there is a desired outcome

Question 8

reusing algorithms

Answer 8

they can be reused with slight changes for solving similar problems

quicker than starting from scratch each time

Question 9

Write an algorithm to make a cup of instant coffee. It should be annotated to show where sequence, selection and iteration have been used [5]

Answer 9

1) fill kettle with water (sequence)
2) turn on kettle (sequence)
3) place coffee in the cup (sequence)
4) check if the water is boiling (selection)
5) if water is not boiling go back to step 4 (iteration)
6) pour water into the cup (sequence)
7) if needed, add milk and sugar (selection)

Question 10

Algorithms use selection and iteration.

Define what is meant by:

a) selection
b) iteration [2]

Answer 10

a) selection in an algorithm is where a decision has to be made and a course of action has to be selected
b) iteration is where some of the steps have to be repeated until there is a required outcome