Answer: A) -1/2 Explanation: Rewrite equation as 122x+1 = 120   Leads to 2x + 1 = 0    Solve for x : x = -1/2

Answer: C) 2/21 Explanation: Given that there are three blue marbles, four red marbles, six green marbles and two yellow marbles.   Probability that both marbles are blue = ³C₂/¹⁵C₂ = (3 x 2)/(15 x 14) = 1/35 Probability that both are yellow = ²C₂/¹⁵C₂ = (2 x 1)/(15 x 14) = 1/105 Probability that one blue and other is yellow = (³C₁ x ²C₁)/¹⁵C₂ = (2 x 3 x 2)/(15 x 14) = 2/35   Required probability = 1/35 + 1/105 + 2/35 = 3/35 + 1/105 = 1/35(3 + 1/3) = 10/(3 x 35) = 2/21

Answer: B) 6 kmph Explanation: Speed of the stream = 1Motor boat speed in still water be = x kmphDown Stream = x + 1 kmphUp Stream = x - 1 kmph[35/(x + 1)] + [35/(x - 1)] = 12x = 6 kmph

Answer: B) Rs. 420 Explanation: As given in the question, Marked price is 25% more than the Cost price. => C.P of the article = 34 x 400 = 300  Now,  Let the original S.P of the article be Rs. P Now the new S.P = P + 16.666 +13.333300 x P  => S.P = 7P6 According to the question, 7P6 - 300 = 2P - 300 => 5P = 1800 => P = Rs. 360 Hence, the increased S.P = 360 x 7/6 = Rs. 420.

Answer: A) 9 Explanation: Speed in still water = Average of Speed in Upstream and speed in Downstream = 1/2 (12 + 6) kmph = 9 kmph.

Answer: B) Rs. 6000 Explanation: The wages of labourers in a factory increases in the ratio 22:25 and there was a reduction in the number of labourers in the ratio 15:11. Find the original wage bill if the present bill is Rs 5000 ?Ratio of increase of wages = 22:25Ratio of decrease of labourers = 15:11Compound ratio of wages of labourers = 22 x 15 : 25 x 11 = 330:275Final bill = Rs. 5000For 275 ratio wages = Rs. 5000For 1 ratio wages = 5000/275For 330 ratio wages = 5000/275 x 330 = Rs. 6000

Answer: C) ओवर हैट स्पष्टीकरण: कंप्यूटर पर स्लॉट कवर कंप्यूटर के अंदर जमा धूल को कम करता है। इसलिए स्लॉट कवर उचित स्थान पर मौजूद होना चाहिए। लापता कवर केस के एयरफ्लो डिज़ाइन को बाधित कर सकते हैं और ओवरहीटिंग की समस्या पैदा कर सकते हैं।

Answer: A) Terrace cultivation Explanation: Hence, soil erosion on hillslopes can be checked by Terrace cultivation.