Question

what are the minimum number of days he needs to practice
till his goal is accomplished
0 8
8 days
8.5 days
9 days
(iv) None of these​

Answer 1

Answer:

8 days he needs to practice till his goal is accomplished

Answer 2

Complete Question :- Ramesh wants to participate in 200 m race. He currently can run that distance in 45 sec.

But he wants to do that in 30 sec. With each day practice, it takes 2 sec less.

(a) Which of the following forms an AP for the above situation?

(i) 45,90 ,180….. (ii) 45, 47, 49….. (iii) 45, 43, 41…. (iv) None of these

(b) What is the minimum number of days he need to practice till his goal is accomplished

(i) 8 days (ii) 8.5 days (iii) 9 days (iv) None of these .

Answer :-

we have,

• T1 = a = 45 seconds .
• d = 2 seconds .

so,

→ T2 = (a - d) = 45 - 2 = 43 seconds .

→ T3 = T2 - d = 43 - 2 = 41 seconds .

then,

→ Required AP series = 45, 43 , 41 ______ (iii) (Ans.)

now, we have,

• a = 45 seconds.
• d = 2 seconds .
• T(n) = 30 seconds (His goal .)

so,

→ a + (n - 1)d = T(n)

→ 45 + (n - 1)(-2) = 30

→ 45 - 2n + 2 = 30

→ 47 - 2n = 30

→ 2n = 47 - 30

→ 2n = 17

→ n = 8.5 days (ii) (Ans.)

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