Listing them all, 10-20-30-40-50-60-70-80-90-100-110-120-130-140 you see you can divide the numbers in half (7 pairs). Alternatively you can take (140-10+10)/2/10, adding that additional +10 in the numerator because it is inclusive, giving you 7. Just adding the top and bottom numbers gives you 10+140 for 150. 150*7 is 1050. 

The sequence is formed by starting with 1 and adding successive powers of 5. The numbers are obtained as follows:

 - the correct response.

In the absence of grouping symbols, the first operations that should  be carried out are exponentiations, followed by multiplications and divisions, followed by additions and subtractions. 

The additions and subtractions are carried out from left to right. Since the addition is the one to the right, it is performed last.

By scoring a 372, Francie was outcored by all of the students who finished in the 401-800 ranges, which add up to:

 students.

She was outscored by at most an additional 17 students (the other 17 in the 301-400 range), for a total of at most

 students.

Francie finished between 97th and 114th place, making 100th place the only possible choice.

The fundamental counting principle says that if you want to determine the number of ways that two independent events can happen, multiply the number of ways each event can happen together. In this case, there are 5 * 7, or 35 unique combinations of pants & shirts Mark can wear. If he wears one combination each day, he can last 35 days, or 5 weeks, without buying new clothes.

This is a permutation problem, because we are looking for the number of groups of winners.  Consider the three positions, and how many choices there are for each position:  There are 20 choices for 1st place, 19 for 2nd place, and 18 for 3rd place.

20, 19, 18     

Multiply to get 6840.

Since this a combination problem and we want to know how many different ways the cookies can be created we can solve this using the Fundamental counting principle. 4 x 3 x 8 = 96

Multiplying each of the possible choices together.

The total number of possible combinations of a series of items is the product of the total possibility for each of the items.  Thus, for the letters, there are 26 possibilities for each of the 3 slots, and for the numbers, there are 10 possibilities for each of the 3 slots.  The total number of combinations is then: 26 x 26 x 26 x 10 x 10 x 10 = 17,576,000 ≈ 18 million.

The formula for the number of lines determined by n points, no three of which are “collinear” (on the same line), is n(n-1)/2. To find the number of lines determined by 8 points, we use 8 in the formula to find 8(8-1)/2=8(7)/2=56/2=28. (The formula is derived from two facts: the fact that each point forms a line with each other point, hence n(n-1), and the fact that this relationship is symmetric (i.e. if a forms a line with b, then b forms a line with a), hence dividing by 2.)

The first person holds 7 hands. The second holds six by virtue of already having help the first person’s hand. This continues until through all 8 people. 7+6+5+4+3+2+1=28.