Question

A triangular board having sides 45m, 30m and 35m is used for advertising. One company uses this board for its advertisement for 4 months. How much rent will the company has to pay if the rent is Rs 3500 per m^2?

(a) Rs 611800

(b) Rs 1835400

(c) Rs 611900

(d) Rs 1835500

The question was posed to me in an interview for internship.

The question is from Heron’s Formula & Area of a Triangle by Heron’s Formula topic in section Heron’s Formula of Mathematics – Class 9

Answer 1

Correct choice is (a) Rs 611800

The explanation: a = 45, b = 30 and c = 35

We know that s = \(\frac{a+b+c}{2} = \frac{45+30+35}{2} = \frac{110}{2}\) = 55

According to heron’s formula, area of the triangle = \(\sqrt{s*(s-a)*(s-b)*(s-c)}\)

= \(\sqrt{55*(55-45)*(55-30)*(55-35)}\)

= \(\sqrt{55*10*25*20}\)

= 524.40 m^2

Now the rent for 1 m^2 = Rs 3500,

then rent for 992.15 m^2 = 524.40 * 3500 = Rs 18,35,400

The rent which we got above is for one year.

The company used the board for 4 months.

Therefore rent for 4 months = Rs \(\frac{18,35,400*4}{12}\)

= Rs 6,11,800.