Count how many learners are left handed (A).
Count the total number of learners in the class (B).
There are 48 learners and 4 of them are left handed.
Therefore, % of left-handed:
=A
B
× 100
=
4
48
× 100
=8,3%
8,3% of the learners in your class are left-handed.
The percentage of right-handed learners:
= 100−8,3
=91,7%91,7% of the learners in your class are right-handed.
Some conversions
From unit: To unit (number of these units per “From unit”):
m mm μm nm
m 1 1000 1 000 000 1 000 000 000
mm 10 −^3 or 1/1000 1 1000 1 000 000
μm
(micrometres)10 −^6 or
1/1 000 00010 −^3 or 1/1000 1 1000nm
(nanometres)10 −^9 or
1/1 000 000 00010 −^6 or
1/1 000 00010 −^3 or 1/1000 11.9 Lab safety procedures DUMMY
The Life Science Laboratory has rules that are enforced as a safety precaution.
These rules are:
- Take care when pouring liquids or powders from one container to another. When
spillages occur you need to call the teacher immediately to assist in cleaning up the
spillage. - Take care when using acids. A good safety precaution is to have a solution of sodium
bicarbonate in the vicinity to neutralise any spills as quickly as possible. - Safety goggles and/ or gloves may need to be worn when doing experimental work,
working with various chemicals, or heating substances, as spitting may occur. - When lighting a Bunsen burner the correct procedure needs to be followed.
- Remember that when heating a substance in a test tube, the mouth of the test tube
must face away from you and members in your group.
Chapter 1. Introduction to Life Sciences 21