Question

Each year, the number of students taught by Mr.Wright increases by 2. The first year, he taught 18 students. The total number of students taught after 25 years can be represented using a expression (image) . How many students has Mr.Wright taught in 25 years?


450

500

1050

2100

Answer 1

In the beginning number of students are 18 .

And each year they increase by 2, that is

18 , 18+2, 18+2+2 , 18+2+2+2,.......

So the series is in arthmetic progression, where first term is 18 and common difference is 2 .

To find the 25th term, we will use the following formula

a(n) = a + (n-1)d = 18+(25-1)*2 = 18 + 48 = 66

And to find the sum , we will use the following formula

S = 0.5 n (a+l), where l is the last term which is 66.

S =0.5*25(18+66) = 1050

Correct option is the third option .

Answer 2

Answer:

1050 which is (C)!

Step-by-step explanation:

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