Question
In a competitive examination containing 100
questions, 1 mark is awarded for every correct answer and ½ mark gets deducted for every wrong answer. If a student attempted all questions and obtained 79 marks, how many wrong answers must he have given?Solution
Let number of questions with right answers = x ∴ No. of questions with wrong answers = 100 – x ∴ Marks obtained for right answers = x ∴ Marks deducted for wrong answers = (100 - x)/ 2 ∴ x - (100 - x) / 2 = 79 ⇒ 2x - 100 + x/ 2 = 79 ⇒ 3x - 100 = 158 ⇒ 3x = 258 ∴ x = 86 ∴ No. of questions with wrong answers (100 – 86) = 14
Find the wrong number in the given number series.
27, 388, 712, 996, 1243, 1452
18Â Â Â Â Â 45 Â Â Â Â Â 90 Â Â Â Â Â Â 235Â Â Â Â Â 450 Â Â Â Â Â 1125 Â Â Â Â Â 2250
...A series is given below which contains a wrong term.
(4c – a – 10) , (3b + a – 1) , (bc + a – 1) , (ac + 7b) , (ab + ac + bc + 18) , (3b<...
Find the wrong number in given series.
918, 943, 992, 1073, 1194, 1388
 7    12     33    126    635  Â
1, 4, 20, 126, 1026, 10170
42, 85, 172, 343, 687, 1375
Find the wrong number in the given number series.
7, 12, 19, 28, 39, 53, 67
3, 15, 35, 63, 99, 143
6.5, 11, 22, 25.5, 51, 54.5
