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Progression Practice Test 1

Question : 20 of 23

Marks: +1, -0

Insert three arithmetic means between 11 and 12:

Solution: 👈: Video Solution

Let

a_1, a_2, a_3

, be three arithmetic mean between 11 and 12

So, the AP series is

11, a_1, a_2, a_3, 12

a is the first term and d is the common difference of AP. Then a = 11

t_5 = a + 5d

\Rightarrow 12 = 11 + 5d

\Rightarrow d = \frac{1}{5}

\therefore a_1 = 11 + d = 11 + \frac{1}{5} = \frac{56}{5}

a_2 = 11 + 2d = 11 + \frac{2}{5} = \frac{57}{5}

a_3 = 11 + 3d = 11 + \frac{3}{5} = \frac{58}{5}

Hence, the required arithmetic means are

\frac{56}{5}, \frac{57}{5}, \frac{58}{5}

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