1. Multiples of 4 lie between 10 and 250: 12, 16, 20, ..., 248 Let the total number of multiples of 4 lie between 10 and 250 be n. Here, a = 12 and d = 16 - 12 = 4. To find: n, where a_n = 248. Given that: a_n = a + (n - 1)d = 248 ⇒ 12 + (n -1)(4) = 248 ⇒ 4(n -1) = 236 ⇒ n - 1 = 236/4 = 59 ⇒ n = 60 HenRead more

    Multiples of 4 lie between 10 and 250: 12, 16, 20, …, 248
    Let the total number of multiples of 4 lie between 10 and 250 be n.
    Here, a = 12 and d = 16 – 12 = 4. To find: n, where a_n = 248.
    Given that: a_n = a + (n – 1)d = 248
    ⇒ 12 + (n -1)(4) = 248 ⇒ 4(n -1) = 236
    ⇒ n – 1 = 236/4 = 59 ⇒ n = 60
    Hence, the total number of multiples of 4 lie between 10 and 250 is 60.

    See less
    • 1
  2. First term of first AP = A = 63 and common difference = D = 65 - 63 = 2 Therefore, A_n = A + (n -1)D ⇒ A_n = 63 + (n -1)2 First term of second AP = a = 3 and common difference = d = 10 - 3 = 7 Therefore, a_n = a + (n -1)d ⇒ a_n = 3 +(n -1)7 According to question, A_n = a_n ⇒ 63 + (n - 1)2 = 3 + (n -Read more

    First term of first AP = A = 63 and common difference = D = 65 – 63 = 2
    Therefore, A_n = A + (n -1)D ⇒ A_n = 63 + (n -1)2
    First term of second AP = a = 3 and common difference = d = 10 – 3 = 7
    Therefore, a_n = a + (n -1)d ⇒ a_n = 3 +(n -1)7
    According to question, A_n = a_n
    ⇒ 63 + (n – 1)2 = 3 + (n -1)7 ⇒ 63 + 2_n – 2 = 3 + 7_n – 7
    ⇒ 65 = 5_n ⇒ n = 13
    Hence, the 13th term of both the APs are equal.

    See less
    • 1
  3. Let the first term of the AP = a and common difference = d Third term = 16 ⇒ a₃ = 16 ⇒ a + 2d = 16 ... (1) 7th term exceeds the 5th term by 12, therefore a₇ = a₅ + 12 ⇒ a + 6d = a + 4d + 12 ⇒ 2d = 12 ⇒ d = 6 Putting the value of d in equation (1), we get a + 2(6) = 16 ⇒ a = 4 Hence, the A.P = a, a +Read more

    Let the first term of the AP = a and common difference = d
    Third term = 16
    ⇒ a₃ = 16 ⇒ a + 2d = 16 … (1)
    7th term exceeds the 5th term by 12, therefore a₇ = a₅ + 12
    ⇒ a + 6d = a + 4d + 12
    ⇒ 2d = 12 ⇒ d = 6
    Putting the value of d in equation (1), we get a + 2(6) = 16
    ⇒ a = 4
    Hence, the A.P = a, a + 2d, … = 4, 10, 16, …

    See less
    • 2
  4. Here, a = - 10, d = 7 - 10 = - 3 and n = 30. Therefore, putting the values in a_n = a + (n -1)d, we get a_30 = 10 +(30 -1) (- 3) ⇒ a_30 = 10 - 87 = - 77 Hence, the option (C) is correct.

    Here, a = – 10, d = 7 – 10 = – 3 and n = 30.
    Therefore, putting the values in a_n = a + (n -1)d, we get
    a_30 = 10 +(30 -1) (- 3)
    ⇒ a_30 = 10 – 87 = – 77
    Hence, the option (C) is correct.

    See less
    • 2
  5. Here, a = - 3, d = - 1/2 (- 3) = 5/2 and n = 11. Therefore, putting the values in a_n = a + (n -1)d, we get a₁₁ = - 3 +(11 -1) (5/2) ⇒ a₁₁ = - 3 + 25 = 22 Hence, the option (B) is correct.

    Here, a = – 3, d = – 1/2 (- 3) = 5/2 and n = 11.
    Therefore, putting the values in a_n = a + (n -1)d, we get
    a₁₁ = – 3 +(11 -1) (5/2)
    ⇒ a₁₁ = – 3 + 25 = 22
    Hence, the option (B) is correct.

    See less
    • 2