A new queen size bed sheet measures 210 cm by 240 cm.
The length and width each shrinks
by 2% after the first washing.
a) What are the dimensions of the
sheet after washing?
b) What is the percent decrease in
the area of the sheet?
Oh

a) The dimensions of the sheet after washing are 205.8 cm and 235.2 cm

b) The percent decrease in the area of the sheet is 3.96%

Step-by-step explanation:

Let us solve the question

a)

∵ A new queen size bed sheet measures 210 cm by 240 cm.

∴ Length = 210 cm and width = 240 cm

∵ The length and width each shrinks by 2%

→ If the length is 100% and the width is 100%, they shrink by 2% each,

   then the new length is 98% of the original length and the new width

   is 98% of the original width

∴ The new length = 210 × 98% = 210 × = 210 × 0.98

∴ The new length = 205.8 cm

∴ The new width = 240 × 98% = 240 × = 240 × 0.98

∴ The new length = 235.2 cm

∴ The dimensions of the sheet after washing are 205.8 cm and 235.2 cm

b)

∵ The area of the rectangle = length × width

∴ The area of the original sheet = 210 × 240 = 50400 cm²

∴ The area of the sheet after washing = 205.8 × 235.2 = 48404.16 cm²

→ Percent of decrease = (decrease ÷ original) × 100%

∵ The decrease in area = 50400 - 48404.16 = 1995.84

∵ The original area = 50400

∴ The percent decrease = (1995.84 ÷ 50400) × 100%

∴ The percent decrease = 3.96%

∴ The percent decrease in the area of the sheet is 3.96%

He should row at the speed of 12 kilometers per hour.

Step-by-step explanation:

Given:

An athlete plans to row upstream a distance of 6 kilometers and then return to his starting point in a total time of 4 hours.

The rate of current is 2 km/hr.

Now, to find how fast should he row.

Let speed of the athlete row be .

Distance = 6 kilometres.

So, to get the time of upstream:

Rate of upstream = .

Time of upstream =

Now, to get the time of downstream:

Rate of upstream=

Time of downstream = .

Now, as given total time 4 hours.

Thus, we set an equation:

Time of upstream + time of downstream = total time.

Multiplying both sides by 6 we get:

Dividing both sides by 2 we get:

Therefore, he should row at the speed of 12 kilometers per hour.