{:("Column A", "Column B"),("The average of the first 10 natural number is ", (a) "20 years"),("If" a:b = 2:3 " and " b:c = 9:7", then "a:b:c " is", (b) 5.5),("If the cost price of an article is Rs. 12 and the", (c) 6:9:7),("selling price of the article is Rs. 15. Find the ",),("profit percentage.",),("In how many years will the amount of Rs. 500", (d) 5%),("double at the rate of 5% p.a under simple interest?",),(,(e) 25%),(,(f) 2:3:7),(,(g) "25 years"),(,(h) 5):}

{:("Column A", "Column B"),("The average of the first 10 natural numbe

1.	{:("Column A", "Column B"),("The average of the first 10 natural number is ", (a) "20 years"),("If" a:b = 2:3 " and " b:c = 9:7", then "a:b:c " is", (b) 5.5),("If the cost price of an article is Rs. 12 and the", (c) 6:9:7),("selling price of the article is Rs. 15. Find the ",),("profit percentage.",),("In how many years will the amount of Rs. 500", (d) 5%),("double at the rate of 5% p.a under simple interest?",),(,(e) 25%),(,(f) 2:3:7),(,(g) "25 years"),(,(h) 5):}
Answer» Solution :(b) : Average `= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)/(10)` `(55)/(10) = 5.5` (c) a:b = 2:3 and b:c = 9:7 a:b = 2:3 `rArr` a:b = 6:9 (Multiplying it by 3) `rArr` a:b = 6:9 and b:c = 9:7 `therefore ` a:b:c = 6:9:7 (E) : C.P = Rs. 12, S.P. = Rs. 15 `therefore` Profit = 15-12 = Rs. 3 Profit% = `("Profit")/("Cost Price") xx 100%` `= (3)/(12) xx 100% = 25%` (a) : Principal = Rs. 500 Amount = Rs. 1000 `therefore` Interest = 1000 - 500 = Rs. 500 `S.I = (P xx T xx R)/(100)` `rArr 500 = (500 xx T xx 5)/(100)` `rArr T = " 20 years"`