Arithmetic Progressions
CH05 Question Bank
CBSE_CH05_QUESTION_BANK
Grade 10
Question:
Which term of the AP $3, 8, 13, 18, \ldots$ is $78$?
Step-by-Step Solution
Key Concept: Set the nth term equal to 78 and solve for n.
$a=3,d=5$. $a_n=3+(n-1)5=78\Rightarrow(n-1)5=75\Rightarrow n-1=15$. [1.0 Mark]
$n=16$. So $78$ is the $16$th term. [1.0 Mark]
Correct Answer:
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