SOLUTIONS TO EXERCISES, LESSON 3
1.
a, d, e (para 3-2a)
2.
b, e (para 3-2d)
3.
a, c (para 3-2d)
4.
sodium thiosulfate (para 3-3a).
5.
leaking (para 3-3a(3))
6.
7.
1 hour (para 3-3b(9)(b))
8.
25, 2 1/2 (para 3-3c(2))
9.
a, b. The multiple-tube method is reliable for detecting coliforms, but the
quantitative results are only a statistical approximation. (para 3-4)
10.
membrane-filter technique (para 3-5b(1))
11.
autoclave (para 3-6b(1) (b))
12.
10, 121 (para 3-6b(2) (a))
13.
BFV = 20 x 100 = 30 ml (para 3-8a(1))
67.
14.
10,30, and 90 ml (para 3-8a(2))
15.
18-22, 35 (para 3-9i)
:
16.
60 36 colonies x 100.= 60 colonies per 100 ml (para 3-10c)
60 ml sample
17.
b, d (paras 3-11a, b)
18.
14 (8 minimum + 1 per 1,000) (para 3-13a)
-
19.
c
(para 3-13b (2))
20.
a
(para 3-13c) Avg density must not exceed 1 per 100 ml, and not more than
1 sample may exceed 4 per 100 ml
End of Lesson 3
MD0160
3-34