how do you solve this problem?

Test Preparation SAT Preparation
1

<p>These are PSAT questions and I feel so dumb not being able to do them...</p>

<pre><code> 5, 9, 1, 2, 2, 3, 5, 9, 1, 2, 2, 3, . . . .
</code></pre>

<p>In the sequence above, the first number is 5. The sequence consists of repetitions of the six numbers 5, 9, 1, 2, 2, and 3. What is the 620th number in the sequence?</p>

<p>A) 1
B) 2
C) 3
D) 5
E) 9 <--- the correct answer</p>

<p>how do you solve?</p>

<p>also:</p>

<p>How many 3-digit positive integers have only odd integers as digits?</p>

<p>and:</p>

<p>A wheel made 3,000 revolutions while traveling 45,000pi inches in a straight line along the ground. What is the radius, in inches, of the wheel?</p>

2

<p>I am probably doing this long handed, but I found a possible solution for the first one:</p>

<p>Ok, you know the pattern: 5 9 1 2 2 3 there are 6 numbers</p>

<p>They want to know the 620th...</p>

<p>that means the 3(in the pattern) will have to be the 6th number, 12th number, 18th number, and so on...</p>

<p>If you divide 620/6 u get 103.3(rep.), divide again with a higher number: 624/6 << looks divisible, and it is! </p>

<p>You should get 104(a whole number! that means the 3 in the pattern is the 624th number.) the 620th number will show up in the pattern repeated 104 times.</p>

<p>Now count backwards from 624 to 620! 623 is 2; 622 is the other 2; 621 is the 1; and lastly 620 is the 9!!! </p>

<h2>Hope that helped a bit :D</h2>

<p>For the Second Problem: (I will need to see the answers, I think I will explain it wrong)</p>

<p>If you work it out a bit the first number that should come in your head is: 111; now work from there:</p>

<p>111; 113; 115; 117; 119; (*5 numbers in 11<em>)
131; 133; 135; 137; 139. (5 numbers in 13</em>)</p>

<p>You shouldn't do much after this...the only odds between 1-10 are 1,3,5,7,and 9. (&6 numbers)</p>

<p>Multiply the 5(*) and 6(&) you should get 30, but you're not done!</p>

<p>There are still the: 311, 313, and so on...sooo: Once again you have to account for the hundreds place digits, which must be 1,3,5,7, and 9. </p>

<p>Mulitply by 6 again. 30*6=180.</p>

<p>That might be the answer... I have to see the answer choices :(</p>

3

<p>For the third problem:</p>

<p>They want the Radius. Lets go more broad first!</p>

<p>Imagine a wheel: O <<wheel</p>

<p>If the wheel traveled 45000pi and made 3000 revolutions, that means in one revolution, you traveled 15pi. <<< That's our Circumference!</p>

<p>C=15pi</p>

<p>15pi=2pi(r)
7.5 inches= r <<radius</p>

4

<p>For Number 2: An odd digit has to be 1,3,5,7,9</p>

<p>There are five different choices for each digit, and there are 3 digits. The answer is:
5<em>5</em>5=125</p>

5

<p>Thanks guys! And to Lasko -- the answer to the second one is not 180 but 125..sorry, I forgot to state the answer to that one. None's solution is correct :]</p>

<p>I hate sequence questions so much.</p>

6

<p>Lol yea, i just found my mistake. Too late for me to edit...</p>

7

<p>for sequence an easier way to do it is jsut do 620/6 and then u get 103.33333333. take the whole number 103 and multiply it by 6 and u get 618.... since it starts all over after the 618th number u coutn the sequence to 620 so 619 - 5 620 - 9 but its essentially the same thing but i find it easier to count forwards</p>