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3.0 ml of raw sewage is diluted to 300 ml. The D.O. concentration of the diluted sample at the beginning of the test was 8 mg/l. After 5 day-incubation at 20°C, the D.O. concentration was 5 mg/l. The BOD of raw sewerage is
A
100 mg/l
B
200 mg/l
C
300 mg/l
D
400 mg/l
Correct Answer:
300 mg/l
In a BOD test, 1.0 ml of raw sewage was diluted to 100 ml and the dissolved oxygen concentration of diluted sample at the beginning was 6 ppm and it was 4 ppm at the end of 5 day incubation at 20°C. The BOD of raw sewage will be
A
100 ppm
B
200 ppm
C
300 ppm
D
400 ppm
What is the mathematical expression of BOD? /P b) BOD = . c) BOD = /P d) BOD = /P
A
BOD = /P
B
(D1-D2)-(B1-B2)f
C
(D1-D2)-(B1-B2)f
D
(D1-D2)-(B1-B2)f
Raw material purchased:
1
st
January, 600 units @ Rs. 12 per unit
12
th
January, 500 units @ Rs. 14 per unit
21
st
January, 300 units @ Rs. 13 per unit
Raw material issued for manufacture:
3
rd
January 300 units
5
th
January 124 units
15
th
January 250 units
16
th
January 300 units
Raw material returned to stores from manufacturing department on 14
th
January, 50 units. The material is issued on First-in-First out method.
The value of material remaining in store on 21
st
January will be:
A
5,775
B
6,100
C
6,350
D
6,600
If a 2% solution of sewage sample is incubated for 5 days at 20°C and the dissolved oxygen depletion was found to be 8 mg/l. The BOD of the sewage is
A
100 mg/l
B
200 mg/l
C
300 mg/l
D
400 mg/l
If the depletion of oxygen is found to be 2.5 mg/litre after incubating 2.5 ml of sewage diluted to 250 ml for 5 days at 20°C, B.O.D. of the sewage is
A
50 mg/l
B
100 mg/l
C
150 mg/l
D
250 mg/l
Statement I A hypothesis test for comparing the variances of two independent populations with the help of variances of two small samples is known as chi-square test.
Statement II To test the hypothesis that the population standard deviation has a specific value on the basis of the values of sample standard deviation of small sized sample, F-test isrelevant.
A
Both statements are correct
B
Both statements are incorrect
C
Statement I is correct, while Statement II is incorrect
D
Statement I is incorrect, while Statement II is correct
A researcher conduct a hypothesis test and observes values from sample mean and sample standard deviation when n = 25, that do not lead to rejection of null hypothesis. He calculates the p value as 0.0667. What will happen to the p value if he observes the same sample mean and standard deviation for a sample > 25?
A
Stay the same
B
Increase
C
Decrease
D
May increase or decrease
In a test of differences between proportions, two samples are taken. In the first sample, a sample size of 100 shows 25 successes. In the second sample, a sample size of 80 shows 25 successes. What would be the value of B in this case?
A
$$\frac{{30}}{{100}} + \frac{{25}}{{80}}$$
B
$$\frac{{30}}{{100}} \times \frac{{25}}{{80}}$$
C
$$\frac{{30 + 25}}{{100}}$$
D
$$\frac{{30}}{{100}} + \frac{{25}}{{180}}$$
The BOD
5
of an effluent from a coke oven plant is 25 mg/L, and the effluent discharge is 4 ML/d. The receiving stream has a BOD
5
of 2 mg/L and the stream flow is 40 ML/d. What will be the BOD
5
in the stream just below the mixing zone?
A
4.5
B
5.2
C
4.1
D
4.8
If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is
A
50 ppm
B
100 ppm
C
150 ppm
D
200 ppm