Manpreet Kaur is the national record holder for women in the shot-put discipline. Her throw of 18.86m at the Asian Grand Prix in 2017 is the maximum distance for an Indian female athlete. Keeping her as a role model, Sanjitha is determined to earn gold in Olympics one day. Initially her throw reached 7.56m only. Being an athlete in school, she regularly practiced both in the mornings and in the evenings and was able to improve the distance by 9 cm every week. During the special camp for 15 days, she started with 40 throws and every day kept increasing the number of throws by 12 to achieve this remarkable progress.

Question 36 ( i )

How many throws Sanjitha practiced on 11^th day of the camp?

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Transcript

There are 2 APs – Throw distance, and Number of Throws Let’s look at one by one Sanjitha’s throw distance Given that, Sanjitha’s initial throw distance was 7.56 m and she improved the distance by 9 cm every week. Improvement every week = 9 cm = 0.09 m Now, Distance Sanjitha throws initially = 7.56 m Distance Sanjitha throws after 1 week = 7.56 + 0.09 = 7.65 m Distance Sanjitha throws after 2 weeks = 7.65 + 0.09 = 7.74 m So, our AP looks like 7.56, 7.65, 7.74… Here, First term = a = 7.56 Common difference = d = 0.09 Sanjitha’s number of throws Given that, Sanjitha started with 40 throws and increased the number of throws by 12 every day. Now, Number of throws in 1st day = 40 Number of throws in 2nd day = 40 + 12 = 52 Number of throws in 3rd day = 52 + 12 = 64 So, our AP looks like 40, 52, 64, … Here, First term = a = 40 Common difference = d = 12 Our Number of Throws AP is 40, 52, 64, … We need to find the Number of throws on the 11th day of the camp i.e. We need to find 𝒂_𝟏𝟏 We know that an = a + (n − 1)d Putting n = 11, a = 40, d = 12 a11 = 40 + (11 − 1) × 12 = 40 + 10 × 12 = 40 + 120 = 160 Thus, Sanjitha practiced 160 throws on 11th day of camp.

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.