All MCQs

The difference of ratio parts is 5, corresponding to 35.
One part is 7, so the larger number is 9 × 7 = 63.

Two centimeters represent 100,000 centimeters in reality.
Since 100,000 cm = 1 km, the answer is 1 kilometer.

For inverse variation, xy is constant.
Since 12 × 4 = 48, x = 48/6 = 8.

For direct variation, x/y is constant.
The constant is 18/6 = 3, so x = 3 × 10 = 30.

The solution contains 4 liters of salt, which remains unchanged.
For salt to be 25%, total volume must be 16 liters, so 6 liters are added.

Thirty percent of 20 liters is 0.30 × 20.
This equals 6 liters.

The total ratio parts are 7, so one part is 35/7 = 5 liters.
Water is two parts, or 10 liters.

The total score is 20 × 60 + 30 × 70 = 3,300.
Dividing by 50 students gives 66.

The weighted sum is 70 × 2 + 90 × 3 = 410.
Dividing by the total weight 5 gives 82.

The original total age is 4 × 25 = 100 years.
The new total is 5 × 27 = 135, so the new age is 35.

The original total is 8 × 15 = 120.
After removing 22, the total is 98, and 98 ÷ 7 = 14.

Total equals average multiplied by the number of values.
Thus, 24 × 5 = 120.