Staff Selection Commission Combined Graduate Level Exam
Question : If $2x+\frac{9}{x}=9$, what is the minimum value of $x^2+\frac{1}{x^2}$?
Option 1: $\frac{95}{36}$
Option 2: $\frac{97}{36}$
Option 3: $\frac{86}{25}$
Option 4: $\frac{623}{27}$
Correct Answer: $\frac{97}{36}$
Solution : Given: $2x+\frac{9}{x}=9$ Multiplying both sides by $x$, we get, $⇒2x^2-9x+9=0$ $⇒(2x-3)(x-3)=0$ So, $x= \frac{3}{2},3$ Putting the values of $x$ in the equation, we get When $x=\frac{3}{2}$, $x^2+\frac{1}{x^2}=(\frac{3}{2})^2+\frac{1}{(\frac{3}{2})^2}=\frac{97}{36}=2.69$ When $x=3$, $x^2+\frac{1}{x^2}=3^2+\frac{1}{3^2}=\frac{82}{9}=9.11$ So, the minimum value is $\frac{97}{36}$. Hence, the correct answer is $\frac{97}{36}$.
Question : If $\left(x+\frac{1}{x}\right)=2 \sqrt{2}$ and $x>1$, what is the value of $\left(x^6-\frac{1}{x^6}\right)$?
Option 1: $140\sqrt{2}$
Option 2: $116\sqrt{2}$
Option 3: $144\sqrt{2}$
Option 4: $128\sqrt{2}$
Correct Answer: $140\sqrt{2}$
Solution : $\left(x+\frac{1}{x}\right)=2 \sqrt{2}$ Squaring both sides. ⇒ $ (x+\frac{1}{x})^2= 8$ ⇒ $(x-\frac{1}{x})^2 = (x+\frac{1}{x})^2-4$ ⇒ $(x-\frac{1}{x})^2=8-4=4$ ⇒ $(x-\frac{1}{x})= 2$ So, $(x^2-\frac{1}{x^2})=(x+\frac{1}{x})(x-\frac{1}{x})= 2\sqrt{2}×2=4\sqrt{2}$ Cubing both sides, we get ⇒ $x^6-\frac{1}{x^6}-3(x^2-\frac{1}{x^2})=64×(2\sqrt{2})$ ⇒ $x^6-\frac{1}{x^6}-3(4\sqrt{2})=128\sqrt{2}$ ⇒ $x^6-\frac{1}{x^6}=140\sqrt{2}$ Hence, the correct answer is $140\sqrt{2}$.
Question : Directions: How many rectangles are there in the given figure?
Option 1: 9
Option 2: 10
Option 3: 11
Option 4: 12
Correct Answer: 11
Solution : The given figure can be labeled as shown below –
There are a total of 11 rectangles in the above figure. They are ABCD, EFGH, IJKL, MFNQ, EMQR, EFNR, QNOD, NJPO, QJPD, RNGH, MFOD.
Hence, the third option is correct.
Question : A television and a refrigerator were sold for Rs. 12,000 each. If the television was sold at a loss of 20% of the cost and the refrigerator at a gain of 20% of the cost, the entire transaction resulted in:
Option 1: no loss or gain
Option 2: loss of Rs. 1000
Option 3: gain of Rs. 1,000
Option 4: loss of Rs. 2,000
Correct Answer: loss of Rs. 1000
Solution : Let the cost price of the television be $x$ and the cost price of the refrigerator be $y$. Given that the television was sold at a loss of 20% of the cost. $⇒12000 = x - 0.20x = 0.80x$ $⇒x = \frac{12000}{0.80}
Question : Select the incorrect statement about Gymnosperms.
Option 1: Gymnosperms are found as woody shrubs, trees or lianas and include no true aquatics and few epiphytes.
Option 2: Gymnosperms are seedless flowering plants.
Option 3: Gymnosperms are typically slow in terms of reproduction; up to a year may pass between pollination and fertilisation and seed maturation may require 3 years.
Option 4: Gymnosperms exhibit cones or strobili and naked seeds, but not flowers.
Correct Answer: Gymnosperms are seedless flowering plants.
Solution : The correct answer is Gymnosperms are seedless flowering plants.
Question : Which of the following states has become India's first carbon-free state?
Option 1: Himachal Pradesh
Option 2: Madhya Pradesh
Option 3: Uttar Pradesh
Option 4: Maharashtra
Correct Answer: Himachal Pradesh
Solution : The correct answer is Himachal Pradesh.
A city must use only renewable energy and eliminate all other non-renewable energy sources to achieve zero carbon emissions; thus, a zero-carbon city is one with a renewable energy economy. Himachal Pradesh wants to be the second carbon-free
Question : Select the option that expresses the given sentence in past tense form.
The declarations which come out from that office are not dependable.
Option 1: The declarations which will come out from that office may not be dependable.
Option 2: The declarations which come out from that office were not dependable.
Option 3: The declarations which came out from that office are not dependable.
Option 4: The declarations which came out from that office were not dependable.
Correct Answer: The declarations which came out from that office were not dependable.
Solution : The correct choice is the fourth option.
The correct sentence is: The declarations which came out from that office were not dependable.
Question : A train travelling at 36 km/h crosses a pole in 25 seconds. How much time (in seconds) will it take to cross a bridge 350 m long?
Option 1: 72
Option 2: 48
Option 3: 60
Option 4: 56
Correct Answer: 60
Solution : Speed of train = $36 × \frac{5}{18}$ = 10 m/s Time taken = 25 seconds Length of train = 25 × 10 = 250 m Length of bridge = 350 m Total length = length of tran + length of bridge Total length = 250
Question : certain substances loose their electrical resistance completely at super low temperature. such substance are called
Option 1: super conductors
Option 2: semi conductors
Option 3: dilectrics
Option 4: perfect conductors
Correct Answer: super conductors
Solution : The correct option is superconductors.
Superconductors are substances that fully loose their electrical resistance at very low temperatures. When Heike Kamerlingh Onnes saw that the electrical resistance of mercury dropped to zero at temperatures close to absolute zero (around 273.15 degrees Celsius), he made
Question : Direction: In the following question, select the one which is different from the other three alternatives.
Option 1: 222
Option 3: 68
Option 4: 125
Correct Answer: 125
Solution : Let's check the options —
First option: 222; 222 ÷ 2 = 111. 222 is an even number.
Second option: 10; 10 ÷ 2 = 5. 10 is an even number.
Third option: 68; 68 ÷ 2 = 34. 68 is an even number.
Fourth
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