Question Detail

10 men, working 6 hours a day can complete a work in 18 days. How many hours a day must 15 men work to complete the work in 12 days ?

4 hours a day
5 hours a day
6 hours a day
7 hours a day

Answer: Option C

Explanation:

More Men, Less Hours {Indirect Proportion}
Less Days, More Hours {Indirect Proportion}
\begin{aligned}
\begin{bmatrix}Men & 15 & 10 \\Days & 12 & 18 \end{bmatrix} :: 6 : x \\
=> x * 15 * 12 = 10 * 18 * 6 \\
=> x = \frac{10*18*6}{15*12} \\
=> x = 6
\end{aligned}

1. A flagstaff 17.5 metre high casts a shadow of length 40.25 metre. The height of building, which casts a shadow of length 28.75 metre under similar conditions will be :

12 metre
12.5 metre
13.5 metre
14 metre

Answer: Option B

Explanation:

Less shadow, Less Height (Direct Proportion)
So, let height of building be x metre
then,
\begin{aligned}
40.25 : 17.5 :: 28.75 : x \\

=> x = \frac{17.5*28.75}{40.25} \\
=> x = 12.5
\end{aligned}

So height of building should be 12.5 metre

2. In a camp, there is a meal for 120 men or 200 children. If 150 children have taken the meal, how many men will be catered to with the remaining meal ?

38 men
32 men
34 men
30 men

Answer: Option D

Explanation:

There is meal for 200 children. 150 children have taken the meal.
Remaining meal is to be catered to 50 children.
Now, 200 children = 120 men

So, 50 Children = 120/200 * 50 = 30 men

3. 4 mat-weavers can weave 4 mats in 4 days. At the same rate, how many mats would be woven by 8 mat weavers in 8 days ?

Answer: Option C

Explanation:

Please always remember, that what exactly we need to calculate before applying chain formula. As in this question we need to find how many mats, RIGHT !
So we will compare everything with "number of mats"
As,

More men, More number of mats (Direct Proportion)
More days, More number of mats (Direct Proportion)

So, it can be solved as,

\begin{aligned}
\begin{bmatrix}Weavers & 4 & 8 \\Days & 4 & 8 \end{bmatrix} :: 4 : x \\

=> x*4*4 = 8*8*4 \\
=> x = 16
\end{aligned}

4. If the price of 23 toys is 276, then what will the price of 12 toys ?

Answer: Option A

Explanation:

Less toys, Less Price (Direct Proportion)
So, let the price be Rs. x
then,
\begin{aligned}
23:12 :: 276:x
=> x = \frac{276*12}{23} \\
=> x = 144
\end{aligned}

So price of 12 toys will be Rs. 144

5. In a dairy farm, 40 cows eat 40 bags of husk in 40 days. In how many days one cow will eat one bag of husk ?

34 days
40 days
46 days
50 days

Answer: Option B

Explanation:

Less Cows, More days (Indirect Proportion)
Less bags, Less days (Direct Proportion)

\begin{aligned}
\begin{bmatrix}Cows & 1 & 40 \\Bags & 40 & 1 \end{bmatrix} :: 40 : x \\
=> x * 40 * 1= 40 * 1 * 40 \\
=> x = 40
\end{aligned}