Math Is Fun Forum

Abeedoodle

Member

Registered: 2008-03-06

Posts: 1

Please Help me understand these problems and how to solve them?

The first problem looks like this:

   4< (sq root symbol) x <9 is equivalent to saying what about x? 

a. 0 < x < 5
b. 0 < x < 65
c. 2 < x < 3
d. 4 < x < 9
e. 16 < x < 81

(what is this symbol: < ) ???

second problem:

If the total cost of x apples is b cents, what is a general formula for the cost, in cents, of y apples?

a. b/xy
b. x/by
c. xy/b
d. by/x
e. bx/y

Third problem:

75% of a class took at least 8 math courses, Of the remaining class members, 60% had taken 6 or 7 math courses. What percent had taken fewer than 6 math courses?

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Please Help me understand these problems and how to solve them?

< means "less than".
So, 4 < √x < 9 means that 4 is less than √x and √x is less than 9.
You can probably pick the right answer now.

To answer the second question, first work out how much one apple would cost.
x apples cost b cents, and so you have that xz = b, where z is the price of one apple.
From there it's easy to find the price of y apples.

In the third question, you're interested in the amount of people who didn't take at least 8 courses, or 6 or 7.

You're told that 75% of people took at least 8 courses, which means that 25% of them didn't.
Similarly, you're told that out of that 25%, 60% of them took 6 or 7 courses, which means that 40% of them didn't.

The answer you want is therefore 40% of 25%, which is 10%.

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Why did the vector cross the road?
It wanted to be normal.