## IGNOU BCA 4th Semester Solved Assignment

### BCSL-044 STATISTICAL TECHNIQUES LAB

#### QUESTIONS SOLVED IN ASSIGNMENT

- A LED light producer tested the life of 30 samples. This data is given in the following table. Perform the tasks given in (i) to (iv) on the data given below using a spreadsheet package:

##### LED light life (in hrs)

38005 40000 35093 33985 24987 34899 44955 34888 33908 34098 27890 23009 34098 45008 45898 24898 30002 34526 41000 23989 34567 23456 43211 54123 12584 36547 14569 321458 25478 36541 41258 25478 26987 35896 39851 48015 41101 37097 41203 15874 31000 24584 41023 36214 39201 37258 34589 27015 29654 28622 - Find the minimum and maximum LED light life using spreadsheet formula.
- Create 10 classes with suitable class intervals and create the frequency distribution. You must use Array formula.
- Find the percentage of LED lights which have less than mean life.
- Draw the histogram for the data above. Also try to relate it to normal distribution curve.

- Perform the following tasks using a spreadsheet (you must either enter necessary formula that are required to calculate the value or you may use spreadsheet function for the same):
- Find the value of t for the give value of degree of freedom and significance level (alpha):

Degree of freedom alpha value 12 0.05 10 0.01 - A company manufactures a type of USB ports which should be 12 mm wide. A sample of 200 such USB ports were taken out of a lot consisting of 50000 ports. The mean sample width was found to be 11.95 mm having a standard deviation of 0.11 mm. Assuming confidence level of 95%, will you accept the USB lot. Justify your answer. Make suitable assumption, if any.

- Find the value of t for the give value of degree of freedom and significance level (alpha):
- A hypothetical petrol pump is equipped with a test measure of 2 litres. A person can use this measure to verify, if s/he has got the right quantity of petrol. It has four filling machine namely A, B, C and D. Every day four samples are taken from every filling machine. The findings are given in the following table:

##### Data of filling machines while measuring 2 litres (in litres)

Sample Manufacturer A B C D 1 2.01 1.89 2.11 1.93 2 2.02 1.87 2.01 1.93 3 1.99 2.02 2.09 1.89 4 1.98 1.97 2.01 2.00 Perform an ANOVA using any software to test (at 5% level) whether all the four filling machines are giving correct amount of petrol. Make suitable assumptions, if any.

- Rainfall of first 15 days of July is recorded in the following table. Use spreadsheet software to find the moving averages for the length of 3 and 5.

Day Rainfall (in mm) 1 15 2 25 3 1 4 0 5 10 6 19 7 30 8 2 9 5 10 22 11 6 12 5 13 4 14 16 15 45 - A company packs flour in sealed packs of 10 kgs. It measures the weight of 5 bags randomly; this measurement is repeated five times in each day. Calculate the control limits for mean and range, and plot the control charts using any statistical software. Make suitable assumptions, if any.

##### The Data is given in following tables

Sample Days The weight of bag (kgs) 1 10.050 9.990 10.175 10.089 10.005 2 10.205 10.045 10.099 9.999 9.975 3 10.153 10.001 10.500 9.979 9.898 4 9.990 9.997 10.050 10.069 10.075 5 10.973 11.045 11.025 11.022 10.999 (Please take the suitable values of d2 , d3, d4 , A2 and other variables.)

- An Umbrella manufacturing company records the sale of Umbrella units in different months as given in the following table. Fit a trend line using any statistical software to this sales data. Make suitable assumptions.

Month Mar Apr May June Jul Aug Sept Sales of Umbrella

(Units)500 1000 3000 7000 5000 2000 400

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