Sequence - Arithmetic Sequences

SOURCE:COMPETITION
Number of Problems: 6. : (Book)

Suppose that ${a_n}$ is an arithmetic sequence with $a_1+a_2+cdots+a_{100}=100 ext{ and } a_{101}+a_{102}+cdots+a_{200}=200.$ What is the value of $a_2 - a_1 ?$

$mathrm{(A) } 0.0001qquad mathrm{(B) } 0.001qquad mathrm{(C) } 0.01qquad mathrm{(D) } 0.1qquad mathrm{(E) }...$

The 챦짭혖rst four terms in an arithmetic sequence are $x+y$ , $x-y$ , $xy$ , and $frac{x}{y}$ , in that order. What is the 챦짭혖fth term?

$extbf{(A)} -frac{15}{8}qquad extbf{(B)} -frac{6}{5}qquad extbf{(C)} 0qquad extbf{(D)} frac{27}{20}qquad extb...$

A grocer makes a display of cans in which the top row has one can and each lower row has two more cans than the row above it. If the display contains 100 cans, how many rows does it contain?

$(mathrm {A}) 5 qquad (mathrm {B}) 8 qquad (mathrm {C}) 9 qquad (mathrm {D}) 10 qquad (mathrm {E}) 11$