vikasp99 wrote:

On a soccer team, one team member is selected at random to be the goalie. What is the probability that a substitute player will be the goalie?

(1) One-sixth of the team members are substitute players.

(2) 18 of the team members are not substitute players.

Dear

vikasp99,

I'm happy to help.

It's helpful to think in terms of two different "baskets" of information. One is

"ratio" information, which includes fractions, percents, and probabilities--1/2 the group, 30% of the group, or the ratio of A to B in the group is 4:7. All of that is the same kind of information: we don't know the exact counts or numbers, and we can figure out anything else in the basket without knowing the counts.

The other is "counts" information, the actual number of individuals in categories. One count tells us nothing about the ratio information, but if we have single count + ratio information, we generally can figure out all the counts.

The prompt is asking for a probability.

Statement #1 give us a fraction, which is ratio information. This is the same basket as the prompt, so we can figure out the probability = 1/6.

Sufficient.

Statement #2 gives us a single count, and we have no ratio information, so we can't figure out anything.

Not sufficient.

Does all this make sense?

Mike

_________________

Mike McGarry

Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)