1. The most common blood typing system divides human blood into four groups: A, B, O, and AB. The following bar
graph presents the frequencies of these types in a sample of
150 blood donors.
a. Which is the most frequent type?
b. True or false: More than half of the individuals in the
The sample had type O blood.
c. True or false: More than twice as many people had type A blood as had type B blood. a)1,b)1,c)1 point
2. The weights of a sample of nine football players are 78, 72, 68, 73, 75, 69, 74, 73, 72. Find the variance and the standard deviation.

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c