Simplify \(7\frac{1}{12}-4\frac{3}{4}+2\frac{1}{2}\)
4
41/6
45/6
51/6
Correct answer is C
\(7\frac{1}{12}-4\frac{3}{4}+2\frac{1}{2}=5\left(\frac{1-9+6}{12}\right)\\
5\left(\frac{-2}{12}\right)\\
=4\left(\frac{12-2}{12}\right)\)
(carry one from 5 and call it 12)
\(4\frac{10}{12}\\
=4\frac{5}{6}\)
If 55\(_x\) + 52\(_x\) = 77\(_{10}\) find X
5
6
7
10
Correct answer is C
5 \(\times\) x\(^1\) + 5 \(\times\) x\(^0\) + 5 \(\times\) x\(^1\) + 2 \(\times\) x\(^0\) = 77
(change all to base 10)
5x + 5 + 5x + 2 = 77
10x + 7 = 77
10x = 77-7
10x = 70
x = 70/10
x = 7
3/10
1/5
1/6
1/10
Correct answer is B
Total possible outcome
12+18+x+30+2x+45 = 105+3x
∴105+3x = 150
3x = 150-105
3x = 45
x = 15
P(obtaining 5) = \(\frac{2x}{(105+3x)}But x= 15\\
=\frac{2(15)}{(105+3(15))}\\
=\frac{30}{(105+45)}\\
=\frac{30}{150}\\
=\frac{1}{5}\)
The probability of picking a letter T from the word OBSTRUCTION is?
1/11
2/11
3/11
4/11
Correct answer is B
OBSTRUCTION
Total possible outcome = 11
Number of chance of getting T = 2
P(picking T) = 2/11
Find the number of ways of selecting 6 out of 10 subjects for an examination
128
216
215
210
Correct answer is D
\(^{10}C_6 = \frac{10!}{(10-6)!6!}\\
=\frac{10!}{4!6!}\\
=\frac{10\times 9\times 8 \times 7 \times 6!}{4\times 3\times 2\times 1 \times 6!}\\
=210\)
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