+0

# If you could explain these to me, that would be greatly appreciated!

0
149
4
+273

I need help asap! Thanks in advance!

Apr 25, 2018

#1
+971
+2

87.

Since there are three digits and each digit has 10 options,

there are a total of:

10^3 ways of identifying students.

The first number can be a 0, since it is not supposed to be a number, just an identification.

10^3 = 1000

Apr 25, 2018
#2
+971
+2

88.

There are a total of:

$$\binom{15}{4}$$

ways to choose the debaters.

This is equal to 1365.

Since we need those four people, with only one way to choose them.

The chance this will happen is 1/1365.

Apr 25, 2018
#3
+3763
+1

89. The probability of choosing a dime first is $$\frac{2}{10}=\frac{1}{5}$$ .

Next, picking a quarter without replacement is just $$\frac{3}{10}$$.

Multiplying, we get $$\frac{1}{5}*\frac{3}{10}=\frac{3}{50}$$

.
Apr 25, 2018
#4
+3763
+1

90.

The total number of marbles: $$12+8+4+16=40$$

Blue Marble: $$\frac{4}{40}=\frac{1}{10}$$

Red marble: $$\frac{12}{40}=\frac{3}{10}$$

So, the answer is just $$\frac{1}{10}*\frac{3}{10}=\boxed{\frac{3}{100}}$$

.
Apr 25, 2018