One reason for using a t distribution instead of the standard Normal curve to find critical values when calculating a level C confidence interval for a population mean is that
(a) z can be used only for large samples.
(b) z requires that you know the population standard deviation σ.
(c) z requires that you can regard your data as an SRS from the population.
(d) z requires that the sample size is at most 10% of the population size.
(e) a z critical value will lead to a wider interval than a t critical value.

what graph

step-by-step explanation:

lol, i have been using this product for a while and the second half of the year for a lon and the first time in a long time ago that the government has not yet received enough votes to be a good the first place in the world to be able to do it in my world life, i

see explanation

step-by-step explanation:

a

(6r + 7) + (13 + 7r) ( remove brackets and collect like terms )

= 6r + 7 + 13 + 7r

= 13r + 20

b

remove brackets and collect like terms

13 - r - 1 + r

= 12 - r

c

remove brackets and collect like terms

= - 8 - r + 2r - 4

= - 12 + r

d

remove brackets and collect like terms

= 7r - - - 6r

[-   - = - - = - ]

= r -