Question
25 men can complete a piece of work in 13 days. One man
starts the work and after every day one more man joins the work and this continues till the work is completed. Then, in how many days will the work be completed?Solution
Let 1 day work of 1 man = 1 units So total work = 25 ×13 = 325 units Suppose after n days work is finished. So, 1 + 2 + ………… +n = 325 ⇒ (n(n+1))/2 = 325 n² + n – 650 = 0 n² + 26n – 25n – 650 = 0 n(n + 26 ) – 25(n + 26) = 0 (n - 25) (n + 26) ∴ n = 25 Hence, the work will be finished in 25 days.
If 30sin4theta; + 45 cos4theta; = 18 . Then find the value of 216 cosec6theta; + 64 sec6
- From the top of a tower, the angle of depression to the top of a man's head is 60°. The man is 4 feet tall and is standing 20 feet away from the base of t...
If acos 3 θ + 3asin 2 θcosθ = m and asin 3 θ + 3asinθcos 2 θ = n, then find the value of (m + n) ...
If √3cosec 2x = 2, then the value of x:
From the top of a building, the angle of depression of two cars on a straight road are 30° and 60° respectively. If the height of the building is 120 ...
Find the value of (1 - sin2q) X (secq + tanq) X (secq - tanq) X cosec2q
- In a triangle ABC, if 5∠A = 3∠B = 15∠C, then find the value of cosA + sin(C + 10 ° )
Relevant for Exams:
