Reliabilityengineers are concerned with the collector current of the power trans
ID: 2918999 • Letter: R
Question
Reliabilityengineers are concerned with the collector current of the power transistor overnormal
receiveroperation. An excellent digital ammeter probe is available, but the data has tobe “read by eye”
and recordedmanually.
Currentreadings were collected once every 15 minutes for approximately five hours ofnormal receiver
operation inthe anticipated receiving environment. The datasheet follows:
Model 167PTReceiver
Q16Collector Current (Units: Amperes)
NormalReceiver Operation in Area 127, Tucson
2100-0145MST, 12/16/2008
Model 2354Digital Ammeter (DC)
Lundy, V.K. Ext. 2975,Reliability
Time CurrentTime Current Time Current Time Current Time Current
2100 1.04 2200 0.97 2300 0.95 0000 0.92 0100 0.85
2115 0.86 2215 1.04 2315 0.91 0015 1.15 0115 1.04
2130 0.97 2230 1.25 2330 1.08 0030 1.01 0130 1.18
2145 1.02 2245 0.90 2345 0.94 0045 1.07 0145 1.06
a) Calculatethe following sample statistics for the collector current data. Include units:
i) Mean
ii) Median
iii) Range
iv) Variance
v) Standard deviation
vi) 1stquartile
vii) 3rd quartile
vii) Interquartile range
b) Constructthe following graphical descriptors for the collector current data. Labelgraphs completely:
i) Run chart
Explanation / Answer
Location Variability
Mean 1.010500 Std Deviation 0.10511
Median 1.015000 Variance 0.01105
Mode 1.040000 Range 0.40000
Interquartile Range 0.13500
75% Q3 1.065
50% Median 1.015
25% Q1 0.930