JEE Main 2015 · 10 Apr · Shift 1 · Mathematics Q67

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MathematicsSingle correct+4 / -1Question 67 of 90

Let the sum of the first three terms of an A.P. be 39 and the sum of its last four terms be 178. If the first term of this A.P. is 10, then the median of the A.P. is :

26.5

29.5

Answer and worked solution

Official answer: C

$3a+3d=39$ with $a=10$ gives $d=3$ . The last four terms sum to $4l-18=178$ , so $l=49$ . The median of an AP is the mean of its first and last terms:
$\frac{10+49}2=29.5.$

Topics:Arithmetic progression Measures of central tendency

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JEE Main 2015 · 10 Apr · Shift 1, Mathematics question 67