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# Daily Math Questions

Registered User Posts: 14 New Member
edited November 2012
Hey guys, I'm prepping for the Dec SAT and I think a daily math questions would help me improve. Can anyone help me with these questions? If you nee help too, feel free to post.

1. Kyle's lock combination consists of 3 two-digit numbers. The combination satisfies the three conditions below.

-One number is odd
-One number is a multiple of 5
-One number is the day of the month of Kyle's birthday

If each number satisfies exactly one of the conditions, which of the following could be the combination of the lock?

A. 14-20-13
B. 14-25-13
C. 15-18-16
D. 20-15-20
E. 34-30-21

I'm confused because A, B, and D all fit the conditions...
Post edited by maraudersmap on

## Replies to: Daily Math Questions

• Registered User Posts: 346 Member
I'm not agreeing with how the question is given to us; but I'll give you the answer they're looking for.

The only thing you missed was the word "one." ONE number is odd. ONE number is a multiple of 5. And ONE number.. you get it.

A. 14-20-13
B. 14-25-13 - Eliminate because it has 2 odd numbers.
C. 15-18-16 - Eliminate because 15 can't satisfy two requirements.
D. 20-15-20 - Eliminate because it has two multiple of 5's.
E. 34-30-21 - Eliminate because 21 and 30 work, but 34 doesn't satisfy the birthday requirement.

A!
• Registered User Posts: 14 New Member
Omg I feel so stupid. Thank you so much!

Here's another one I need help with:

Let x be defined as [x]=x^2-x for all values of x. If [a]=a-2, what is the value of a?

A. 1
B. 1/2
C. 3/2
D. 6/5
E. 3
• Registered User Posts: 2,118 Senior Member
This is not an SAT question, it's just an SAT-level question I made up.

Q: If p and q are positive integers such that pq = 50, which of the following cannot equal (p^2)q?

A: 50
B: 100
C: 200
D: 250
E: 500
• Registered User Posts: 2,118 Senior Member
@maraudersmap, are you sure your question is correctly typed? Here's what I did:

[a] = a^2 - a = a - 2

a^2 - 2a + 2 = 0

a = (2 +- sqrt(4 - 8))/2, i.e. two complex solutions.
• Registered User Posts: 43 Junior Member
I'm pretty sure the question is: Let x be defined as [x]=x^2-x for all values of x. If [a]=[a-2], what is the value of a?
• Registered User Posts: 14 New Member
The question is typed correctly, [ ] is one of those weird symbols
• Registered User Posts: 2,118 Senior Member
[a] = a-2 and [a] = [a-2] mean completely different things...
• Registered User Posts: 14 New Member
sorry, you guys are right. It's [a-2]
• Registered User Posts: 2,118 Senior Member
Then it's just

a^2 - a = (a-2)^2 - (a-2)

a^2 - a = a^2 - 5a + 6 (upon expanding, simplifying). a^2 cancels, leaving

-a = -5a + 6 --> a = 3/2
• Registered User Posts: 14 New Member
Thank you very much! I'll post when I have more questions, I'm currently not at home haha [:
• Registered User Posts: 91 Junior Member