Question
The average age of a group of eight children is 9 years.
Two children, whose ages were 7 years more and 5 years more than the average age, left. Two new children, whose average age is 4 years more than the given average age, join the group. Find the new average age.Solution
Initial sum of the ages of 8 children = 9 x 8 = 72 years Ages of the children leaving: 9 + 7 = 16 years and 9 + 5 = 14 years, Sum of the ages of children leaving = 16 + 14 = 30 years Sum of the ages after two children left = 72 - 30 = 42 years Sum of the ages of 2 new children = (9 + 4) x 2 = 26 years Total sum of the ages with new children = 42 + 26 = 68 years Number of children now= 8 - 2 + 2 = 8 New average age = 68/8 = 8.5 years
Prove the identity: tan² θ + 1 = sec² θ
Train ‘X’ takes 54 seconds to pass a tree and 48 seconds to completely cross train ‘Y’ when they are moving in opposite directions. If the speed...
A person who spends 55% of his salary saves the remainder. His salary goes up by 15%, but his savings stay the same, and he now spends Rs. 3,300 more. D...
The inequality | 2x – 3 | < 5 is satisfied for:
The ratio of the length and area of a rectangle is 1:39. And the ratio of length and breadth 4:3. Find the perimeter of the rectangle.
{656.08 + 89.13 - 291.91 + 319.31 - 402.98} = ?
Two individuals, A and B, started a business by investing ₹7,200 and ₹11,700, respectively. After 20 months, A withdrew his entire investment. At th...
A man invested a certain amount of sum at 12.5% per annum simple interest and earned an interest of Rs.3000 after 5 years. If the same amount is investe...
An item (Burger) is sold at a profit of 20%. Determine the cost price of the item (Burger).
Statement I: The selling pric...
A and B start a business together. A invests ₹20,000 for 6 months, and B invests ₹30,000 for 8 months. If the total profit is ₹6000, how much does...
