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
What will come in place of (?) question mark in the given number series.
12, 27, 44, 65, ?, 139
124, 107, 91, ? , 62, 49
257, 399, 566, ?, 983, 1237Â
12   18   31   51   ?   112
37, 57, 82, ?, 147, 187
41, 82, ?, 984, 4920, 29520Â Â Â
What will come in place of the question mark (?) in the following series?
4, 3, 7, 26, 101, ?
15, 31, 67, 131, ?, 375
- What will come in place of the question mark (?) in the following series?
121, 115, 102, 82, 55, ? 188    178    158   ?     88    38
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