The marketing manager of Warts fast-food has implemented a new promotional ads. The ads is shown in different social media platforms. The average sales in 30 days, before and after the new ads was shown, were gathered from 12 branches.

The data is presented below.

SALES IN HUNDRED THOUSAND PESOS
Branches	A	B	C	D	E	F	G	H	I	J	K	L
Before	3.6	2.7	4.9	1.8	3.4	4.1	5.2	6.1	4.8	5.3	6.6	7.2
After	4.1	2.5	5.1	2.3	3.8	4.1	4.9	6	4.9	5.1	6.4	7.5

At 0.05 level of significance, is the ads effective? Perform a 4-step hypothesis testing.