Can anybody help me with SAT Math questions?
Please explain to me!
1. The average of 21 consecutive integers is 10, what is the average of the first two integers and the last two integers?
A. 9 B. 10 C. 11 D. 12 E. 13
2. A man invests $10,000 part in a bank account which pays 6% interest per year and the reminder in a stock which pays a yearly dividend of 7%. If in one year he earns a total of $665 from both interest and dividends together, how much, in dollars, did he invest in stock?
3. If n! is defined as 1*2 *3 *…*n for all positive integers, if x equals 10! * 11! * 12! *… *20!, what is the value of the hundred digit of x?
4. Triangles ABC and ABD share side AB. Triangle ABC has area Q, and triang’e ABD has area R. If AD is longer than AC and BD is longer than BC, which of the following could be true?
I. R>Q
II. R=Q
III.R
A. I only B. III only C. I and II only D. I and III only E. I, II, and III
1.
the ave = the 11th no.
av =(a1+a2+a20+a21)/4
=(10-10+10-9+10+9+10+10)/4 =10
2.
s*0.07+(10000-s)*.06 = 665
s*0.01 = 665 – 600 = 65
S = $6500 (invested in stock)
10000 -6500 = $3500 invested in bank account.
3. 10! has 2,5,10 as factors producing 100
9! has 2,5 as factors producing 10
at least from 10!*9! will produce 1000
therefor the hundred digit is zero
4. assuming CD=CB+BD .. I. R>Q
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