Answer:
1. 24
2.
where n denotes number of days.
3. 70
Explanation:
1.
Consider the sequence:
![12,14,16,18,...](https://img.qammunity.org/2021/formulas/mathematics/high-school/73eu9t5ddtx8dxjckf76xah1hx3rjimkly.png)
Here,
![14-12=2\\16-14=2\\18-16=2](https://img.qammunity.org/2021/formulas/mathematics/high-school/5obwhauchm5nwu96xdvujl0fkgiut2zao8.png)
Take the common difference as d = 2 and the first term as a = 12
Use the formula:
![a_n=a+(n-1)d](https://img.qammunity.org/2021/formulas/mathematics/high-school/ldz5qtrumnj2gsu0pzuqyauj1d3zaaigaw.png)
To find expected gain at the end of the week, find
![a_7](https://img.qammunity.org/2021/formulas/mathematics/high-school/tbp8oo3uq1s6h83rsu4s6spqmiamccbyz2.png)
![a_7=12+(7-1)2\\=12+6(2)\\=12+12\\=24](https://img.qammunity.org/2021/formulas/mathematics/high-school/ymfka4xz2vbm7729r9xjdd0hq4l6t6t4o4.png)
2.
Yes, the gain shows the pattern.
Put
in
![a_n=a+(n-1)d](https://img.qammunity.org/2021/formulas/mathematics/high-school/ldz5qtrumnj2gsu0pzuqyauj1d3zaaigaw.png)
![a_n=12+(n-1)2\\=12+2n-2\\=10+2n](https://img.qammunity.org/2021/formulas/mathematics/high-school/abbgbk033lahucjfs2dgmi3k1e3ossbcuq.png)
Here, n denotes number of days.
3.
To find expected gain at the end of 30 days, put
in
![a_n=10+2n](https://img.qammunity.org/2021/formulas/mathematics/high-school/gevluzx06gng0hafp1rrosbg03s0dx6b0x.png)
![a_(30)=10+2(30)\\ =10+60\\=70](https://img.qammunity.org/2021/formulas/mathematics/high-school/jto193e6bp9wocnu35jqoekq0sn1ck4opl.png)