Answer:
For tap water
Mean = 7.5
Median = 7.485
Mode = 7.47
For bottled water
Mean = 5.1942
Median = 5.22
Mode = 5.26
b) Tap water is alkaline while bottled water is acidic
c) For 7.10 recorded as 1.70, mean value will decrease to 7.05
Step-by-step explanation:
Given;
pH readings for tap water
7.64, 7.45, 7.47, 7.50, 7.68, 7.69, 7.45, 7.10, 7.56, 7.47, 7.52, 7.47
Now,
Mean =
Sum of all readings
= 7.64 + 7.45+ 7.47+ 7.50+ 7.68+ 7.69+ 7.45+ 7.10+ 7.56+ 7.47+7.52+7.47
= 90
Number of readings = 12
or
Mean =
or
Mean = 7.5
For median
Putting the data set in ascending numerical order
7.10
, 7.45, 7.45, 7.47, 7.47, 7.47
, 7.50, 7.52, 7.56, 7.64
, 7.68, 7.69
Thus,
median = = 7.485
Mode = number that appears most frequently = 7.47
Now for bottled water
Readings are :
5.15 5.09 5.26 5.20 5.02 5.23 5.28 5.26 5.13 5.26 5.21 5.24
Mean =
Sum of all readings =
5.15 + 5.09 + 5.26 + 5.20 + 5.02 + 5.23 + 5.28 + 5.26 + 5.13 + 5.26 + 5.21 + 5.24
= 62.33
Number of readings = 12
Mean =
or
Mean = 5.1942
Putting the data set in ascending numerical order
5.02, 5.09, 5.13, 5.15, 5.20, 5.21, 5.23, 5.24, 5.26, 5.26, 5.26, 5.28
median = = 5.22
Mode = number that appears most frequently = 5.26
b) Tap water is alkaline while bottled water is acidic
c) For 7.10 recorded as 1.70
Mean =
Sum of all readings
= 7.64 + 7.45+ 7.47+ 7.50+ 7.68+ 7.69+ 7.45+ 1.70+ 7.56+ 7.47+7.52+7.47
= 84.6
Number of readings = 12
or
Mean =
or
Mean = 7.05
Hence , the mean value will decrease to 7.05