WAEC Financial Accounting 2011 Theory question 101

Any three:
(a) Computer error: a wrong or unexpected result produced by a computer, caused by faulty hardware, faulty software or wrong input/operation.
(b) Garbage in, garbage out (GIGO): the computer only processes what it is given, so wrong input data or instructions produce wrong output.
(c) Downtime: the period during which a computer system is not working (breakdown, repair or power failure) and cannot be used.
(d) Debugging: finding and removing errors (bugs) in a computer program.
(e) Computer service bureau/cyber-café: a business that has computers and sells data-processing, internet or computer services to firms and members of the public for a fee.

Choose the three you can explain best; one clear definition each.