Summary statistics Q
2.
The numbers of units of electricity, * kWh (kilowatt-hours), used by 50 customers of an energy firm in a period of one month are summarised as follows.
Sigma(x) = 17100
Sigma(x)2= 6115 108
(i) Calculate the mean and standard deviation of x.
[3]
(ii) The cost, £y, of the electricity used by each customer is given by the formula y = 0.108x + 7.2. Use
your answers to part (i) to deduce the mean and standard deviation of the costs of the electricity used by these customers.
why is the answer to part ii SD
0.108x73.8 and why has the +7.2 been disgarded?
i hope that makes sense?
The numbers of units of electricity, * kWh (kilowatt-hours), used by 50 customers of an energy firm in a period of one month are summarised as follows.
Sigma(x) = 17100
Sigma(x)2= 6115 108
(i) Calculate the mean and standard deviation of x.
[3]
(ii) The cost, £y, of the electricity used by each customer is given by the formula y = 0.108x + 7.2. Use
your answers to part (i) to deduce the mean and standard deviation of the costs of the electricity used by these customers.
why is the answer to part ii SD
0.108x73.8 and why has the +7.2 been disgarded?
i hope that makes sense?
Original post by uhhhh6678987654
2.
The numbers of units of electricity, * kWh (kilowatt-hours), used by 50 customers of an energy firm in a period of one month are summarised as follows.
Sigma(x) = 17100
Sigma(x)2= 6115 108
(i) Calculate the mean and standard deviation of x.
[3]
(ii) The cost, £y, of the electricity used by each customer is given by the formula y = 0.108x + 7.2. Use
your answers to part (i) to deduce the mean and standard deviation of the costs of the electricity used by these customers.
why is the answer to part ii SD
0.108x73.8 and why has the +7.2 been disgarded?
i hope that makes sense?
The numbers of units of electricity, * kWh (kilowatt-hours), used by 50 customers of an energy firm in a period of one month are summarised as follows.
Sigma(x) = 17100
Sigma(x)2= 6115 108
(i) Calculate the mean and standard deviation of x.
[3]
(ii) The cost, £y, of the electricity used by each customer is given by the formula y = 0.108x + 7.2. Use
your answers to part (i) to deduce the mean and standard deviation of the costs of the electricity used by these customers.
why is the answer to part ii SD
0.108x73.8 and why has the +7.2 been disgarded?
i hope that makes sense?
Standard deviation is a measure of dispersion about the mean. The constant 7.2 affects (shifts) the mean but not the way the data is dispersed about the mean.
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